Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

8 files changed, 1649 insertions, 0 deletions

diff --git a/Documentation/doc-guide/contributing.rst b/Documentation/doc-guide/contributing.rst
new file mode 100644
index 0000000000..d4793826ad
--- /dev/null
+++ b/Documentation/doc-guide/contributing.rst
@@ -0,0 +1,296 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+How to help improve kernel documentation
+========================================
+
+Documentation is an important part of any software-development project.
+Good documentation helps to bring new developers in and helps established
+developers work more effectively.  Without top-quality documentation, a lot
+of time is wasted in reverse-engineering the code and making avoidable
+mistakes.
+
+Unfortunately, the kernel's documentation currently falls far short of what
+it needs to be to support a project of this size and importance.
+
+This guide is for contributors who would like to improve that situation.
+Kernel documentation improvements can be made by developers at a variety of
+skill levels; they are a relatively easy way to learn the kernel process in
+general and find a place in the community.  The bulk of what follows is the
+documentation maintainer's list of tasks that most urgently need to be
+done.
+
+The documentation TODO list
+---------------------------
+
+There is an endless list of tasks that need to be carried out to get our
+documentation to where it should be.  This list contains a number of
+important items, but is far from exhaustive; if you see a different way to
+improve the documentation, please do not hold back!
+
+Addressing warnings
+~~~~~~~~~~~~~~~~~~~
+
+The documentation build currently spews out an unbelievable number of
+warnings.  When you have that many, you might as well have none at all;
+people ignore them, and they will never notice when their work adds new
+ones.  For this reason, eliminating warnings is one of the highest-priority
+tasks on the documentation TODO list.  The task itself is reasonably
+straightforward, but it must be approached in the right way to be
+successful.
+
+Warnings issued by a compiler for C code can often be dismissed as false
+positives, leading to patches aimed at simply shutting the compiler up.
+Warnings from the documentation build almost always point at a real
+problem; making those warnings go away requires understanding the problem
+and fixing it at its source.  For this reason, patches fixing documentation
+warnings should probably not say "fix a warning" in the changelog title;
+they should indicate the real problem that has been fixed.
+
+Another important point is that documentation warnings are often created by
+problems in kerneldoc comments in C code.  While the documentation
+maintainer appreciates being copied on fixes for these warnings, the
+documentation tree is often not the right one to actually carry those
+fixes; they should go to the maintainer of the subsystem in question.
+
+For example, in a documentation build I grabbed a pair of warnings nearly
+at random::
+
+  ./drivers/devfreq/devfreq.c:1818: warning: bad line:
+  	- Resource-managed devfreq_register_notifier()
+  ./drivers/devfreq/devfreq.c:1854: warning: bad line:
+	- Resource-managed devfreq_unregister_notifier()
+
+(The lines were split for readability).
+
+A quick look at the source file named above turned up a couple of kerneldoc
+comments that look like this::
+
+  /**
+   * devm_devfreq_register_notifier()
+	  - Resource-managed devfreq_register_notifier()
+   * @dev:	The devfreq user device. (parent of devfreq)
+   * @devfreq:	The devfreq object.
+   * @nb:		The notifier block to be unregistered.
+   * @list:	DEVFREQ_TRANSITION_NOTIFIER.
+   */
+
+The problem is the missing "*", which confuses the build system's
+simplistic idea of what C comment blocks look like.  This problem had been
+present since that comment was added in 2016 — a full four years.  Fixing
+it was a matter of adding the missing asterisks.  A quick look at the
+history for that file showed what the normal format for subject lines is,
+and ``scripts/get_maintainer.pl`` told me who should receive it (pass paths to
+your patches as arguments to scripts/get_maintainer.pl).  The resulting patch
+looked like this::
+
+  [PATCH] PM / devfreq: Fix two malformed kerneldoc comments
+
+  Two kerneldoc comments in devfreq.c fail to adhere to the required format,
+  resulting in these doc-build warnings:
+
+    ./drivers/devfreq/devfreq.c:1818: warning: bad line:
+  	  - Resource-managed devfreq_register_notifier()
+    ./drivers/devfreq/devfreq.c:1854: warning: bad line:
+	  - Resource-managed devfreq_unregister_notifier()
+
+  Add a couple of missing asterisks and make kerneldoc a little happier.
+
+  Signed-off-by: Jonathan Corbet <corbet@lwn.net>
+  ---
+   drivers/devfreq/devfreq.c | 4 ++--
+   1 file changed, 2 insertions(+), 2 deletions(-)
+
+  diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
+  index 57f6944d65a6..00c9b80b3d33 100644
+  --- a/drivers/devfreq/devfreq.c
+  +++ b/drivers/devfreq/devfreq.c
+  @@ -1814,7 +1814,7 @@ static void devm_devfreq_notifier_release(struct device *dev, void *res)
+
+   /**
+    * devm_devfreq_register_notifier()
+  -	- Resource-managed devfreq_register_notifier()
+  + *	- Resource-managed devfreq_register_notifier()
+    * @dev:	The devfreq user device. (parent of devfreq)
+    * @devfreq:	The devfreq object.
+    * @nb:		The notifier block to be unregistered.
+  @@ -1850,7 +1850,7 @@ EXPORT_SYMBOL(devm_devfreq_register_notifier);
+
+   /**
+    * devm_devfreq_unregister_notifier()
+  -	- Resource-managed devfreq_unregister_notifier()
+  + *	- Resource-managed devfreq_unregister_notifier()
+    * @dev:	The devfreq user device. (parent of devfreq)
+    * @devfreq:	The devfreq object.
+    * @nb:		The notifier block to be unregistered.
+  --
+  2.24.1
+
+The entire process only took a few minutes.  Of course, I then found that
+somebody else had fixed it in a separate tree, highlighting another lesson:
+always check linux-next to see if a problem has been fixed before you dig
+into it.
+
+Other fixes will take longer, especially those relating to structure
+members or function parameters that lack documentation.  In such cases, it
+is necessary to work out what the role of those members or parameters is
+and describe them correctly.  Overall, this task gets a little tedious at
+times, but it's highly important.  If we can actually eliminate warnings
+from the documentation build, then we can start expecting developers to
+avoid adding new ones.
+
+Languishing kerneldoc comments
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Developers are encouraged to write kerneldoc comments for their code, but
+many of those comments are never pulled into the docs build.  That makes
+this information harder to find and, for example, makes Sphinx unable to
+generate links to that documentation.  Adding ``kernel-doc`` directives to
+the documentation to bring those comments in can help the community derive
+the full value of the work that has gone into creating them.
+
+The ``scripts/find-unused-docs.sh`` tool can be used to find these
+overlooked comments.
+
+Note that the most value comes from pulling in the documentation for
+exported functions and data structures.  Many subsystems also have
+kerneldoc comments for internal use; those should not be pulled into the
+documentation build unless they are placed in a document that is
+specifically aimed at developers working within the relevant subsystem.
+
+
+Typo fixes
+~~~~~~~~~~
+
+Fixing typographical or formatting errors in the documentation is a quick
+way to figure out how to create and send patches, and it is a useful
+service.  I am always willing to accept such patches.  That said, once you
+have fixed a few, please consider moving on to more advanced tasks, leaving
+some typos for the next beginner to address.
+
+Please note that some things are *not* typos and should not be "fixed":
+
+ - Both American and British English spellings are allowed within the
+   kernel documentation.  There is no need to fix one by replacing it with
+   the other.
+
+ - The question of whether a period should be followed by one or two spaces
+   is not to be debated in the context of kernel documentation.  Other
+   areas of rational disagreement, such as the "Oxford comma", are also
+   off-topic here.
+
+As with any patch to any project, please consider whether your change is
+really making things better.
+
+Ancient documentation
+~~~~~~~~~~~~~~~~~~~~~
+
+Some kernel documentation is current, maintained, and useful.  Some
+documentation is ... not.  Dusty, old, and inaccurate documentation can
+mislead readers and casts doubt on our documentation as a whole.  Anything
+that can be done to address such problems is more than welcome.
+
+Whenever you are working with a document, please consider whether it is
+current, whether it needs updating, or whether it should perhaps be removed
+altogether.  There are a number of warning signs that you can pay attention
+to here:
+
+ - References to 2.x kernels
+ - Pointers to SourceForge repositories
+ - Nothing but typo fixes in the history for several years
+ - Discussion of pre-Git workflows
+
+The best thing to do, of course, would be to bring the documentation
+current, adding whatever information is needed.  Such work often requires
+the cooperation of developers familiar with the subsystem in question, of
+course.  Developers are often more than willing to cooperate with people
+working to improve the documentation when asked nicely, and when their
+answers are listened to and acted upon.
+
+Some documentation is beyond hope; we occasionally find documents that
+refer to code that was removed from the kernel long ago, for example.
+There is surprising resistance to removing obsolete documentation, but we
+should do that anyway.  Extra cruft in our documentation helps nobody.
+
+In cases where there is perhaps some useful information in a badly outdated
+document, and you are unable to update it, the best thing to do may be to
+add a warning at the beginning.  The following text is recommended::
+
+  .. warning ::
+  	This document is outdated and in need of attention.  Please use
+	this information with caution, and please consider sending patches
+	to update it.
+
+That way, at least our long-suffering readers have been warned that the
+document may lead them astray.
+
+Documentation coherency
+~~~~~~~~~~~~~~~~~~~~~~~
+
+The old-timers around here will remember the Linux books that showed up on
+the shelves in the 1990s.  They were simply collections of documentation
+files scrounged from various locations on the net.  The books have (mostly)
+improved since then, but the kernel's documentation is still mostly built
+on that model.  It is thousands of files, almost each of which was written
+in isolation from all of the others.  We don't have a coherent body of
+kernel documentation; we have thousands of individual documents.
+
+We have been trying to improve the situation through the creation of
+a set of "books" that group documentation for specific readers.  These
+include:
+
+ - Documentation/admin-guide/index.rst
+ - Documentation/core-api/index.rst
+ - Documentation/driver-api/index.rst
+ - Documentation/userspace-api/index.rst
+
+As well as this book on documentation itself.
+
+Moving documents into the appropriate books is an important task and needs
+to continue.  There are a couple of challenges associated with this work,
+though.  Moving documentation files creates short-term pain for the people
+who work with those files; they are understandably unenthusiastic about
+such changes.  Usually the case can be made to move a document once; we
+really don't want to keep shifting them around, though.
+
+Even when all documents are in the right place, though, we have only
+managed to turn a big pile into a group of smaller piles.  The work of
+trying to knit all of those documents together into a single whole has not
+yet begun.  If you have bright ideas on how we could proceed on that front,
+we would be more than happy to hear them.
+
+Stylesheet improvements
+~~~~~~~~~~~~~~~~~~~~~~~
+
+With the adoption of Sphinx we have much nicer-looking HTML output than we
+once did.  But it could still use a lot of improvement; Donald Knuth and
+Edward Tufte would be unimpressed.  That requires tweaking our stylesheets
+to create more typographically sound, accessible, and readable output.
+
+Be warned: if you take on this task you are heading into classic bikeshed
+territory.  Expect a lot of opinions and discussion for even relatively
+obvious changes.  That is, alas, the nature of the world we live in.
+
+Non-LaTeX PDF build
+~~~~~~~~~~~~~~~~~~~
+
+This is a decidedly nontrivial task for somebody with a lot of time and
+Python skills.  The Sphinx toolchain is relatively small and well
+contained; it is easy to add to a development system.  But building PDF or
+EPUB output requires installing LaTeX, which is anything but small or well
+contained.  That would be a nice thing to eliminate.
+
+The original hope had been to use the rst2pdf tool (https://rst2pdf.org/)
+for PDF generation, but it turned out to not be up to the task.
+Development work on rst2pdf seems to have picked up again in recent times,
+though, which is a hopeful sign.  If a suitably motivated developer were to
+work with that project to make rst2pdf work with the kernel documentation
+build, the world would be eternally grateful.
+
+Write more documentation
+~~~~~~~~~~~~~~~~~~~~~~~~
+
+Naturally, there are massive parts of the kernel that are severely
+underdocumented.  If you have the knowledge to document a specific kernel
+subsystem and the desire to do so, please do not hesitate to do some
+writing and contribute the result to the kernel.  Untold numbers of kernel
+developers and users will thank you.
diff --git a/Documentation/doc-guide/hello.dot b/Documentation/doc-guide/hello.dot
new file mode 100644
index 0000000000..504621dfc5
--- /dev/null
+++ b/Documentation/doc-guide/hello.dot
@@ -0,0 +1,3 @@
+graph G {
+      Hello -- World
+}
diff --git a/Documentation/doc-guide/index.rst b/Documentation/doc-guide/index.rst
new file mode 100644
index 0000000000..7c7d977846
--- /dev/null
+++ b/Documentation/doc-guide/index.rst
@@ -0,0 +1,21 @@
+.. _doc_guide:
+
+=================================
+How to write kernel documentation
+=================================
+
+.. toctree::
+   :maxdepth: 1
+
+   sphinx
+   kernel-doc
+   parse-headers
+   contributing
+   maintainer-profile
+
+.. only::  subproject and html
+
+   Indices
+   =======
+
+   * :ref:`genindex`
diff --git a/Documentation/doc-guide/kernel-doc.rst b/Documentation/doc-guide/kernel-doc.rst
new file mode 100644
index 0000000000..6ad72ac686
--- /dev/null
+++ b/Documentation/doc-guide/kernel-doc.rst
@@ -0,0 +1,552 @@
+.. title:: Kernel-doc comments
+
+===========================
+Writing kernel-doc comments
+===========================
+
+The Linux kernel source files may contain structured documentation
+comments in the kernel-doc format to describe the functions, types
+and design of the code. It is easier to keep documentation up-to-date
+when it is embedded in source files.
+
+.. note:: The kernel-doc format is deceptively similar to javadoc,
+   gtk-doc or Doxygen, yet distinctively different, for historical
+   reasons. The kernel source contains tens of thousands of kernel-doc
+   comments. Please stick to the style described here.
+
+.. note:: kernel-doc does not cover Rust code: please see
+   Documentation/rust/general-information.rst instead.
+
+The kernel-doc structure is extracted from the comments, and proper
+`Sphinx C Domain`_ function and type descriptions with anchors are
+generated from them. The descriptions are filtered for special kernel-doc
+highlights and cross-references. See below for details.
+
+.. _Sphinx C Domain: http://www.sphinx-doc.org/en/stable/domains.html
+
+Every function that is exported to loadable modules using
+``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` should have a kernel-doc
+comment. Functions and data structures in header files which are intended
+to be used by modules should also have kernel-doc comments.
+
+It is good practice to also provide kernel-doc formatted documentation
+for functions externally visible to other kernel files (not marked
+``static``). We also recommend providing kernel-doc formatted
+documentation for private (file ``static``) routines, for consistency of
+kernel source code layout. This is lower priority and at the discretion
+of the maintainer of that kernel source file.
+
+How to format kernel-doc comments
+---------------------------------
+
+The opening comment mark ``/**`` is used for kernel-doc comments. The
+``kernel-doc`` tool will extract comments marked this way. The rest of
+the comment is formatted like a normal multi-line comment with a column
+of asterisks on the left side, closing with ``*/`` on a line by itself.
+
+The function and type kernel-doc comments should be placed just before
+the function or type being described in order to maximise the chance
+that somebody changing the code will also change the documentation. The
+overview kernel-doc comments may be placed anywhere at the top indentation
+level.
+
+Running the ``kernel-doc`` tool with increased verbosity and without actual
+output generation may be used to verify proper formatting of the
+documentation comments. For example::
+
+	scripts/kernel-doc -v -none drivers/foo/bar.c
+
+The documentation format is verified by the kernel build when it is
+requested to perform extra gcc checks::
+
+	make W=n
+
+Function documentation
+----------------------
+
+The general format of a function and function-like macro kernel-doc comment is::
+
+  /**
+   * function_name() - Brief description of function.
+   * @arg1: Describe the first argument.
+   * @arg2: Describe the second argument.
+   *        One can provide multiple line descriptions
+   *        for arguments.
+   *
+   * A longer description, with more discussion of the function function_name()
+   * that might be useful to those using or modifying it. Begins with an
+   * empty comment line, and may include additional embedded empty
+   * comment lines.
+   *
+   * The longer description may have multiple paragraphs.
+   *
+   * Context: Describes whether the function can sleep, what locks it takes,
+   *          releases, or expects to be held. It can extend over multiple
+   *          lines.
+   * Return: Describe the return value of function_name.
+   *
+   * The return value description can also have multiple paragraphs, and should
+   * be placed at the end of the comment block.
+   */
+
+The brief description following the function name may span multiple lines, and
+ends with an argument description, a blank comment line, or the end of the
+comment block.
+
+Function parameters
+~~~~~~~~~~~~~~~~~~~
+
+Each function argument should be described in order, immediately following
+the short function description.  Do not leave a blank line between the
+function description and the arguments, nor between the arguments.
+
+Each ``@argument:`` description may span multiple lines.
+
+.. note::
+
+   If the ``@argument`` description has multiple lines, the continuation
+   of the description should start at the same column as the previous line::
+
+      * @argument: some long description
+      *            that continues on next lines
+
+   or::
+
+      * @argument:
+      *		some long description
+      *		that continues on next lines
+
+If a function has a variable number of arguments, its description should
+be written in kernel-doc notation as::
+
+      * @...: description
+
+Function context
+~~~~~~~~~~~~~~~~
+
+The context in which a function can be called should be described in a
+section named ``Context``. This should include whether the function
+sleeps or can be called from interrupt context, as well as what locks
+it takes, releases and expects to be held by its caller.
+
+Examples::
+
+  * Context: Any context.
+  * Context: Any context. Takes and releases the RCU lock.
+  * Context: Any context. Expects <lock> to be held by caller.
+  * Context: Process context. May sleep if @gfp flags permit.
+  * Context: Process context. Takes and releases <mutex>.
+  * Context: Softirq or process context. Takes and releases <lock>, BH-safe.
+  * Context: Interrupt context.
+
+Return values
+~~~~~~~~~~~~~
+
+The return value, if any, should be described in a dedicated section
+named ``Return``.
+
+.. note::
+
+  #) The multi-line descriptive text you provide does *not* recognize
+     line breaks, so if you try to format some text nicely, as in::
+
+	* Return:
+	* %0 - OK
+	* %-EINVAL - invalid argument
+	* %-ENOMEM - out of memory
+
+     this will all run together and produce::
+
+	Return: 0 - OK -EINVAL - invalid argument -ENOMEM - out of memory
+
+     So, in order to produce the desired line breaks, you need to use a
+     ReST list, e. g.::
+
+      * Return:
+      * * %0		- OK to runtime suspend the device
+      * * %-EBUSY	- Device should not be runtime suspended
+
+  #) If the descriptive text you provide has lines that begin with
+     some phrase followed by a colon, each of those phrases will be taken
+     as a new section heading, which probably won't produce the desired
+     effect.
+
+Structure, union, and enumeration documentation
+-----------------------------------------------
+
+The general format of a struct, union, and enum kernel-doc comment is::
+
+  /**
+   * struct struct_name - Brief description.
+   * @member1: Description of member1.
+   * @member2: Description of member2.
+   *           One can provide multiple line descriptions
+   *           for members.
+   *
+   * Description of the structure.
+   */
+
+You can replace the ``struct`` in the above example with ``union`` or
+``enum``  to describe unions or enums. ``member`` is used to mean struct
+and union member names as well as enumerations in an enum.
+
+The brief description following the structure name may span multiple
+lines, and ends with a member description, a blank comment line, or the
+end of the comment block.
+
+Members
+~~~~~~~
+
+Members of structs, unions and enums should be documented the same way
+as function parameters; they immediately succeed the short description
+and may be multi-line.
+
+Inside a struct or union description, you can use the ``private:`` and
+``public:`` comment tags. Structure fields that are inside a ``private:``
+area are not listed in the generated output documentation.
+
+The ``private:`` and ``public:`` tags must begin immediately following a
+``/*`` comment marker. They may optionally include comments between the
+``:`` and the ending ``*/`` marker.
+
+Example::
+
+  /**
+   * struct my_struct - short description
+   * @a: first member
+   * @b: second member
+   * @d: fourth member
+   *
+   * Longer description
+   */
+  struct my_struct {
+      int a;
+      int b;
+  /* private: internal use only */
+      int c;
+  /* public: the next one is public */
+      int d;
+  };
+
+Nested structs/unions
+~~~~~~~~~~~~~~~~~~~~~
+
+It is possible to document nested structs and unions, like::
+
+      /**
+       * struct nested_foobar - a struct with nested unions and structs
+       * @memb1: first member of anonymous union/anonymous struct
+       * @memb2: second member of anonymous union/anonymous struct
+       * @memb3: third member of anonymous union/anonymous struct
+       * @memb4: fourth member of anonymous union/anonymous struct
+       * @bar: non-anonymous union
+       * @bar.st1: struct st1 inside @bar
+       * @bar.st2: struct st2 inside @bar
+       * @bar.st1.memb1: first member of struct st1 on union bar
+       * @bar.st1.memb2: second member of struct st1 on union bar
+       * @bar.st2.memb1: first member of struct st2 on union bar
+       * @bar.st2.memb2: second member of struct st2 on union bar
+       */
+      struct nested_foobar {
+        /* Anonymous union/struct*/
+        union {
+          struct {
+            int memb1;
+            int memb2;
+          };
+          struct {
+            void *memb3;
+            int memb4;
+          };
+        };
+        union {
+          struct {
+            int memb1;
+            int memb2;
+          } st1;
+          struct {
+            void *memb1;
+            int memb2;
+          } st2;
+        } bar;
+      };
+
+.. note::
+
+   #) When documenting nested structs or unions, if the struct/union ``foo``
+      is named, the member ``bar`` inside it should be documented as
+      ``@foo.bar:``
+   #) When the nested struct/union is anonymous, the member ``bar`` in it
+      should be documented as ``@bar:``
+
+In-line member documentation comments
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+The structure members may also be documented in-line within the definition.
+There are two styles, single-line comments where both the opening ``/**`` and
+closing ``*/`` are on the same line, and multi-line comments where they are each
+on a line of their own, like all other kernel-doc comments::
+
+  /**
+   * struct foo - Brief description.
+   * @foo: The Foo member.
+   */
+  struct foo {
+        int foo;
+        /**
+         * @bar: The Bar member.
+         */
+        int bar;
+        /**
+         * @baz: The Baz member.
+         *
+         * Here, the member description may contain several paragraphs.
+         */
+        int baz;
+        union {
+                /** @foobar: Single line description. */
+                int foobar;
+        };
+        /** @bar2: Description for struct @bar2 inside @foo */
+        struct {
+                /**
+                 * @bar2.barbar: Description for @barbar inside @foo.bar2
+                 */
+                int barbar;
+        } bar2;
+  };
+
+Typedef documentation
+---------------------
+
+The general format of a typedef kernel-doc comment is::
+
+  /**
+   * typedef type_name - Brief description.
+   *
+   * Description of the type.
+   */
+
+Typedefs with function prototypes can also be documented::
+
+  /**
+   * typedef type_name - Brief description.
+   * @arg1: description of arg1
+   * @arg2: description of arg2
+   *
+   * Description of the type.
+   *
+   * Context: Locking context.
+   * Return: Meaning of the return value.
+   */
+   typedef void (*type_name)(struct v4l2_ctrl *arg1, void *arg2);
+
+Highlights and cross-references
+-------------------------------
+
+The following special patterns are recognized in the kernel-doc comment
+descriptive text and converted to proper reStructuredText markup and `Sphinx C
+Domain`_ references.
+
+.. attention:: The below are **only** recognized within kernel-doc comments,
+	       **not** within normal reStructuredText documents.
+
+``funcname()``
+  Function reference.
+
+``@parameter``
+  Name of a function parameter. (No cross-referencing, just formatting.)
+
+``%CONST``
+  Name of a constant. (No cross-referencing, just formatting.)
+
+````literal````
+  A literal block that should be handled as-is. The output will use a
+  ``monospaced font``.
+
+  Useful if you need to use special characters that would otherwise have some
+  meaning either by kernel-doc script or by reStructuredText.
+
+  This is particularly useful if you need to use things like ``%ph`` inside
+  a function description.
+
+``$ENVVAR``
+  Name of an environment variable. (No cross-referencing, just formatting.)
+
+``&struct name``
+  Structure reference.
+
+``&enum name``
+  Enum reference.
+
+``&typedef name``
+  Typedef reference.
+
+``&struct_name->member`` or ``&struct_name.member``
+  Structure or union member reference. The cross-reference will be to the struct
+  or union definition, not the member directly.
+
+``&name``
+  A generic type reference. Prefer using the full reference described above
+  instead. This is mostly for legacy comments.
+
+Cross-referencing from reStructuredText
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+No additional syntax is needed to cross-reference the functions and types
+defined in the kernel-doc comments from reStructuredText documents.
+Just end function names with ``()`` and write ``struct``, ``union``, ``enum``
+or ``typedef`` before types.
+For example::
+
+  See foo().
+  See struct foo.
+  See union bar.
+  See enum baz.
+  See typedef meh.
+
+However, if you want custom text in the cross-reference link, that can be done
+through the following syntax::
+
+  See :c:func:`my custom link text for function foo <foo>`.
+  See :c:type:`my custom link text for struct bar <bar>`.
+
+For further details, please refer to the `Sphinx C Domain`_ documentation.
+
+Overview documentation comments
+-------------------------------
+
+To facilitate having source code and comments close together, you can include
+kernel-doc documentation blocks that are free-form comments instead of being
+kernel-doc for functions, structures, unions, enums, or typedefs. This could be
+used for something like a theory of operation for a driver or library code, for
+example.
+
+This is done by using a ``DOC:`` section keyword with a section title.
+
+The general format of an overview or high-level documentation comment is::
+
+  /**
+   * DOC: Theory of Operation
+   *
+   * The whizbang foobar is a dilly of a gizmo. It can do whatever you
+   * want it to do, at any time. It reads your mind. Here's how it works.
+   *
+   * foo bar splat
+   *
+   * The only drawback to this gizmo is that is can sometimes damage
+   * hardware, software, or its subject(s).
+   */
+
+The title following ``DOC:`` acts as a heading within the source file, but also
+as an identifier for extracting the documentation comment. Thus, the title must
+be unique within the file.
+
+=============================
+Including kernel-doc comments
+=============================
+
+The documentation comments may be included in any of the reStructuredText
+documents using a dedicated kernel-doc Sphinx directive extension.
+
+The kernel-doc directive is of the format::
+
+  .. kernel-doc:: source
+     :option:
+
+The *source* is the path to a source file, relative to the kernel source
+tree. The following directive options are supported:
+
+export: *[source-pattern ...]*
+  Include documentation for all functions in *source* that have been exported
+  using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` either in *source* or in any
+  of the files specified by *source-pattern*.
+
+  The *source-pattern* is useful when the kernel-doc comments have been placed
+  in header files, while ``EXPORT_SYMBOL`` and ``EXPORT_SYMBOL_GPL`` are next to
+  the function definitions.
+
+  Examples::
+
+    .. kernel-doc:: lib/bitmap.c
+       :export:
+
+    .. kernel-doc:: include/net/mac80211.h
+       :export: net/mac80211/*.c
+
+internal: *[source-pattern ...]*
+  Include documentation for all functions and types in *source* that have
+  **not** been exported using ``EXPORT_SYMBOL`` or ``EXPORT_SYMBOL_GPL`` either
+  in *source* or in any of the files specified by *source-pattern*.
+
+  Example::
+
+    .. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c
+       :internal:
+
+identifiers: *[ function/type ...]*
+  Include documentation for each *function* and *type* in *source*.
+  If no *function* is specified, the documentation for all functions
+  and types in the *source* will be included.
+
+  Examples::
+
+    .. kernel-doc:: lib/bitmap.c
+       :identifiers: bitmap_parselist bitmap_parselist_user
+
+    .. kernel-doc:: lib/idr.c
+       :identifiers:
+
+no-identifiers: *[ function/type ...]*
+  Exclude documentation for each *function* and *type* in *source*.
+
+  Example::
+
+    .. kernel-doc:: lib/bitmap.c
+       :no-identifiers: bitmap_parselist
+
+functions: *[ function/type ...]*
+  This is an alias of the 'identifiers' directive and deprecated.
+
+doc: *title*
+  Include documentation for the ``DOC:`` paragraph identified by *title* in
+  *source*. Spaces are allowed in *title*; do not quote the *title*. The *title*
+  is only used as an identifier for the paragraph, and is not included in the
+  output. Please make sure to have an appropriate heading in the enclosing
+  reStructuredText document.
+
+  Example::
+
+    .. kernel-doc:: drivers/gpu/drm/i915/intel_audio.c
+       :doc: High Definition Audio over HDMI and Display Port
+
+Without options, the kernel-doc directive includes all documentation comments
+from the source file.
+
+The kernel-doc extension is included in the kernel source tree, at
+``Documentation/sphinx/kerneldoc.py``. Internally, it uses the
+``scripts/kernel-doc`` script to extract the documentation comments from the
+source.
+
+.. _kernel_doc:
+
+How to use kernel-doc to generate man pages
+-------------------------------------------
+
+If you just want to use kernel-doc to generate man pages you can do this
+from the kernel git tree::
+
+  $ scripts/kernel-doc -man \
+    $(git grep -l '/\*\*' -- :^Documentation :^tools) \
+    | scripts/split-man.pl /tmp/man
+
+Some older versions of git do not support some of the variants of syntax for
+path exclusion.  One of the following commands may work for those versions::
+
+  $ scripts/kernel-doc -man \
+    $(git grep -l '/\*\*' -- . ':!Documentation' ':!tools') \
+    | scripts/split-man.pl /tmp/man
+
+  $ scripts/kernel-doc -man \
+    $(git grep -l '/\*\*' -- . ":(exclude)Documentation" ":(exclude)tools") \
+    | scripts/split-man.pl /tmp/man
diff --git a/Documentation/doc-guide/maintainer-profile.rst b/Documentation/doc-guide/maintainer-profile.rst
new file mode 100644
index 0000000000..755d39f0d4
--- /dev/null
+++ b/Documentation/doc-guide/maintainer-profile.rst
@@ -0,0 +1,45 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Documentation subsystem maintainer entry profile
+================================================
+
+The documentation "subsystem" is the central coordinating point for the
+kernel's documentation and associated infrastructure.  It covers the
+hierarchy under Documentation/ (with the exception of
+Documentation/devicetree), various utilities under scripts/ and, at least
+some of the time, LICENSES/.
+
+It's worth noting, though, that the boundaries of this subsystem are rather
+fuzzier than normal.  Many other subsystem maintainers like to keep control
+of portions of Documentation/, and many more freely apply changes there
+when it is convenient.  Beyond that, much of the kernel's documentation is
+found in the source as kerneldoc comments; those are usually (but not
+always) maintained by the relevant subsystem maintainer.
+
+The mailing list for documentation is linux-doc@vger.kernel.org.  Patches
+should be made against the docs-next tree whenever possible.
+
+Submit checklist addendum
+-------------------------
+
+When making documentation changes, you should actually build the
+documentation and ensure that no new errors or warnings have been
+introduced.  Generating HTML documents and looking at the result will help
+to avoid unsightly misunderstandings about how things will be rendered.
+
+Key cycle dates
+---------------
+
+Patches can be sent anytime, but response will be slower than usual during
+the merge window.  The docs tree tends to close late before the merge
+window opens, since the risk of regressions from documentation patches is
+low.
+
+Review cadence
+--------------
+
+I am the sole maintainer for the documentation subsystem, and I am doing
+the work on my own time, so the response to patches will occasionally be
+slow.  I try to always send out a notification when a patch is merged (or
+when I decide that one cannot be).  Do not hesitate to send a ping if you
+have not heard back within a week of sending a patch.
diff --git a/Documentation/doc-guide/parse-headers.rst b/Documentation/doc-guide/parse-headers.rst
new file mode 100644
index 0000000000..5da0046f70
--- /dev/null
+++ b/Documentation/doc-guide/parse-headers.rst
@@ -0,0 +1,192 @@
+===========================
+Including uAPI header files
+===========================
+
+Sometimes, it is useful to include header files and C example codes in
+order to describe the userspace API and to generate cross-references
+between the code and the documentation. Adding cross-references for
+userspace API files has an additional vantage: Sphinx will generate warnings
+if a symbol is not found at the documentation. That helps to keep the
+uAPI documentation in sync with the Kernel changes.
+The :ref:`parse_headers.pl <parse_headers>` provide a way to generate such
+cross-references. It has to be called via Makefile, while building the
+documentation. Please see ``Documentation/userspace-api/media/Makefile`` for an example
+about how to use it inside the Kernel tree.
+
+.. _parse_headers:
+
+parse_headers.pl
+^^^^^^^^^^^^^^^^
+
+NAME
+****
+
+
+parse_headers.pl - parse a C file, in order to identify functions, structs,
+enums and defines and create cross-references to a Sphinx book.
+
+
+SYNOPSIS
+********
+
+
+\ **parse_headers.pl**\  [<options>] <C_FILE> <OUT_FILE> [<EXCEPTIONS_FILE>]
+
+Where <options> can be: --debug, --help or --usage.
+
+
+OPTIONS
+*******
+
+
+
+\ **--debug**\
+
+ Put the script in verbose mode, useful for debugging.
+
+
+
+\ **--usage**\
+
+ Prints a brief help message and exits.
+
+
+
+\ **--help**\
+
+ Prints a more detailed help message and exits.
+
+
+DESCRIPTION
+***********
+
+
+Convert a C header or source file (C_FILE), into a ReStructured Text
+included via ..parsed-literal block with cross-references for the
+documentation files that describe the API. It accepts an optional
+EXCEPTIONS_FILE with describes what elements will be either ignored or
+be pointed to a non-default reference.
+
+The output is written at the (OUT_FILE).
+
+It is capable of identifying defines, functions, structs, typedefs,
+enums and enum symbols and create cross-references for all of them.
+It is also capable of distinguish #define used for specifying a Linux
+ioctl.
+
+The EXCEPTIONS_FILE contain two types of statements: \ **ignore**\  or \ **replace**\ .
+
+The syntax for the ignore tag is:
+
+
+ignore \ **type**\  \ **name**\
+
+The \ **ignore**\  means that it won't generate cross references for a
+\ **name**\  symbol of type \ **type**\ .
+
+The syntax for the replace tag is:
+
+
+replace \ **type**\  \ **name**\  \ **new_value**\
+
+The \ **replace**\  means that it will generate cross references for a
+\ **name**\  symbol of type \ **type**\ , but, instead of using the default
+replacement rule, it will use \ **new_value**\ .
+
+For both statements, \ **type**\  can be either one of the following:
+
+
+\ **ioctl**\
+
+ The ignore or replace statement will apply to ioctl definitions like:
+
+ #define	VIDIOC_DBG_S_REGISTER 	 _IOW('V', 79, struct v4l2_dbg_register)
+
+
+
+\ **define**\
+
+ The ignore or replace statement will apply to any other #define found
+ at C_FILE.
+
+
+
+\ **typedef**\
+
+ The ignore or replace statement will apply to typedef statements at C_FILE.
+
+
+
+\ **struct**\
+
+ The ignore or replace statement will apply to the name of struct statements
+ at C_FILE.
+
+
+
+\ **enum**\
+
+ The ignore or replace statement will apply to the name of enum statements
+ at C_FILE.
+
+
+
+\ **symbol**\
+
+ The ignore or replace statement will apply to the name of enum value
+ at C_FILE.
+
+ For replace statements, \ **new_value**\  will automatically use :c:type:
+ references for \ **typedef**\ , \ **enum**\  and \ **struct**\  types. It will use :ref:
+ for \ **ioctl**\ , \ **define**\  and \ **symbol**\  types. The type of reference can
+ also be explicitly defined at the replace statement.
+
+
+
+EXAMPLES
+********
+
+
+ignore define _VIDEODEV2_H
+
+
+Ignore a #define _VIDEODEV2_H at the C_FILE.
+
+ignore symbol PRIVATE
+
+
+On a struct like:
+
+enum foo { BAR1, BAR2, PRIVATE };
+
+It won't generate cross-references for \ **PRIVATE**\ .
+
+replace symbol BAR1 :c:type:\`foo\`
+replace symbol BAR2 :c:type:\`foo\`
+
+
+On a struct like:
+
+enum foo { BAR1, BAR2, PRIVATE };
+
+It will make the BAR1 and BAR2 enum symbols to cross reference the foo
+symbol at the C domain.
+
+
+BUGS
+****
+
+
+Report bugs to Mauro Carvalho Chehab <mchehab@kernel.org>
+
+
+COPYRIGHT
+*********
+
+
+Copyright (c) 2016 by Mauro Carvalho Chehab <mchehab+samsung@kernel.org>.
+
+License GPLv2: GNU GPL version 2 <https://gnu.org/licenses/gpl.html>.
+
+This is free software: you are free to change and redistribute it.
+There is NO WARRANTY, to the extent permitted by law.
diff --git a/Documentation/doc-guide/sphinx.rst b/Documentation/doc-guide/sphinx.rst
new file mode 100644
index 0000000000..cd8ad79044
--- /dev/null
+++ b/Documentation/doc-guide/sphinx.rst
@@ -0,0 +1,530 @@
+.. _sphinxdoc:
+
+=====================================
+Using Sphinx for kernel documentation
+=====================================
+
+The Linux kernel uses `Sphinx`_ to generate pretty documentation from
+`reStructuredText`_ files under ``Documentation``. To build the documentation in
+HTML or PDF formats, use ``make htmldocs`` or ``make pdfdocs``. The generated
+documentation is placed in ``Documentation/output``.
+
+.. _Sphinx: http://www.sphinx-doc.org/
+.. _reStructuredText: http://docutils.sourceforge.net/rst.html
+
+The reStructuredText files may contain directives to include structured
+documentation comments, or kernel-doc comments, from source files. Usually these
+are used to describe the functions and types and design of the code. The
+kernel-doc comments have some special structure and formatting, but beyond that
+they are also treated as reStructuredText.
+
+Finally, there are thousands of plain text documentation files scattered around
+``Documentation``. Some of these will likely be converted to reStructuredText
+over time, but the bulk of them will remain in plain text.
+
+.. _sphinx_install:
+
+Sphinx Install
+==============
+
+The ReST markups currently used by the Documentation/ files are meant to be
+built with ``Sphinx`` version 1.7 or higher.
+
+There's a script that checks for the Sphinx requirements. Please see
+:ref:`sphinx-pre-install` for further details.
+
+Most distributions are shipped with Sphinx, but its toolchain is fragile,
+and it is not uncommon that upgrading it or some other Python packages
+on your machine would cause the documentation build to break.
+
+A way to avoid that is to use a different version than the one shipped
+with your distributions. In order to do so, it is recommended to install
+Sphinx inside a virtual environment, using ``virtualenv-3``
+or ``virtualenv``, depending on how your distribution packaged Python 3.
+
+.. note::
+
+   #) It is recommended to use the RTD theme for html output. Depending
+      on the Sphinx version, it should be installed separately,
+      with ``pip install sphinx_rtd_theme``.
+
+In summary, if you want to install Sphinx version 2.4.4, you should do::
+
+       $ virtualenv sphinx_2.4.4
+       $ . sphinx_2.4.4/bin/activate
+       (sphinx_2.4.4) $ pip install -r Documentation/sphinx/requirements.txt
+
+After running ``. sphinx_2.4.4/bin/activate``, the prompt will change,
+in order to indicate that you're using the new environment. If you
+open a new shell, you need to rerun this command to enter again at
+the virtual environment before building the documentation.
+
+Image output
+------------
+
+The kernel documentation build system contains an extension that
+handles images on both GraphViz and SVG formats (see
+:ref:`sphinx_kfigure`).
+
+For it to work, you need to install both GraphViz and ImageMagick
+packages. If those packages are not installed, the build system will
+still build the documentation, but won't include any images at the
+output.
+
+PDF and LaTeX builds
+--------------------
+
+Such builds are currently supported only with Sphinx versions 2.4 and higher.
+
+For PDF and LaTeX output, you'll also need ``XeLaTeX`` version 3.14159265.
+
+Depending on the distribution, you may also need to install a series of
+``texlive`` packages that provide the minimal set of functionalities
+required for ``XeLaTeX`` to work.
+
+Math Expressions in HTML
+------------------------
+
+Some ReST pages contain math expressions. Due to the way Sphinx works,
+those expressions are written using LaTeX notation.
+There are two options for Sphinx to render math expressions in html output.
+One is an extension called `imgmath`_ which converts math expressions into
+images and embeds them in html pages.
+The other is an extension called `mathjax`_ which delegates math rendering
+to JavaScript capable web browsers.
+The former was the only option for pre-6.1 kernel documentation and it
+requires quite a few texlive packages including amsfonts and amsmath among
+others.
+
+Since kernel release 6.1, html pages with math expressions can be built
+without installing any texlive packages. See `Choice of Math Renderer`_ for
+further info.
+
+.. _imgmath: https://www.sphinx-doc.org/en/master/usage/extensions/math.html#module-sphinx.ext.imgmath
+.. _mathjax: https://www.sphinx-doc.org/en/master/usage/extensions/math.html#module-sphinx.ext.mathjax
+
+.. _sphinx-pre-install:
+
+Checking for Sphinx dependencies
+--------------------------------
+
+There's a script that automatically check for Sphinx dependencies. If it can
+recognize your distribution, it will also give a hint about the install
+command line options for your distro::
+
+	$ ./scripts/sphinx-pre-install
+	Checking if the needed tools for Fedora release 26 (Twenty Six) are available
+	Warning: better to also install "texlive-luatex85".
+	You should run:
+
+		sudo dnf install -y texlive-luatex85
+		/usr/bin/virtualenv sphinx_2.4.4
+		. sphinx_2.4.4/bin/activate
+		pip install -r Documentation/sphinx/requirements.txt
+
+	Can't build as 1 mandatory dependency is missing at ./scripts/sphinx-pre-install line 468.
+
+By default, it checks all the requirements for both html and PDF, including
+the requirements for images, math expressions and LaTeX build, and assumes
+that a virtual Python environment will be used. The ones needed for html
+builds are assumed to be mandatory; the others to be optional.
+
+It supports two optional parameters:
+
+``--no-pdf``
+	Disable checks for PDF;
+
+``--no-virtualenv``
+	Use OS packaging for Sphinx instead of Python virtual environment.
+
+
+Sphinx Build
+============
+
+The usual way to generate the documentation is to run ``make htmldocs`` or
+``make pdfdocs``. There are also other formats available: see the documentation
+section of ``make help``. The generated documentation is placed in
+format-specific subdirectories under ``Documentation/output``.
+
+To generate documentation, Sphinx (``sphinx-build``) must obviously be
+installed.  For PDF output you'll also need ``XeLaTeX`` and ``convert(1)``
+from ImageMagick (https://www.imagemagick.org).\ [#ink]_ All of these are
+widely available and packaged in distributions.
+
+To pass extra options to Sphinx, you can use the ``SPHINXOPTS`` make
+variable. For example, use ``make SPHINXOPTS=-v htmldocs`` to get more verbose
+output.
+
+It is also possible to pass an extra DOCS_CSS overlay file, in order to customize
+the html layout, by using the ``DOCS_CSS`` make variable.
+
+By default, the "Alabaster" theme is used to build the HTML documentation;
+this theme is bundled with Sphinx and need not be installed separately.
+The Sphinx theme can be overridden by using the ``DOCS_THEME`` make variable.
+
+There is another make variable ``SPHINXDIRS``, which is useful when test
+building a subset of documentation.  For example, you can build documents
+under ``Documentation/doc-guide`` by running
+``make SPHINXDIRS=doc-guide htmldocs``.
+The documentation section of ``make help`` will show you the list of
+subdirectories you can specify.
+
+To remove the generated documentation, run ``make cleandocs``.
+
+.. [#ink] Having ``inkscape(1)`` from Inkscape (https://inkscape.org)
+	  as well would improve the quality of images embedded in PDF
+	  documents, especially for kernel releases 5.18 and later.
+
+Choice of Math Renderer
+-----------------------
+
+Since kernel release 6.1, mathjax works as a fallback math renderer for
+html output.\ [#sph1_8]_
+
+Math renderer is chosen depending on available commands as shown below:
+
+.. table:: Math Renderer Choices for HTML
+
+    ============= ================= ============
+    Math renderer Required commands Image format
+    ============= ================= ============
+    imgmath       latex, dvipng     PNG (raster)
+    mathjax
+    ============= ================= ============
+
+The choice can be overridden by setting an environment variable
+``SPHINX_IMGMATH`` as shown below:
+
+.. table:: Effect of Setting ``SPHINX_IMGMATH``
+
+    ====================== ========
+    Setting                Renderer
+    ====================== ========
+    ``SPHINX_IMGMATH=yes`` imgmath
+    ``SPHINX_IMGMATH=no``  mathjax
+    ====================== ========
+
+.. [#sph1_8] Fallback of math renderer requires Sphinx >=1.8.
+
+
+Writing Documentation
+=====================
+
+Adding new documentation can be as simple as:
+
+1. Add a new ``.rst`` file somewhere under ``Documentation``.
+2. Refer to it from the Sphinx main `TOC tree`_ in ``Documentation/index.rst``.
+
+.. _TOC tree: http://www.sphinx-doc.org/en/stable/markup/toctree.html
+
+This is usually good enough for simple documentation (like the one you're
+reading right now), but for larger documents it may be advisable to create a
+subdirectory (or use an existing one). For example, the graphics subsystem
+documentation is under ``Documentation/gpu``, split to several ``.rst`` files,
+and has a separate ``index.rst`` (with a ``toctree`` of its own) referenced from
+the main index.
+
+See the documentation for `Sphinx`_ and `reStructuredText`_ on what you can do
+with them. In particular, the Sphinx `reStructuredText Primer`_ is a good place
+to get started with reStructuredText. There are also some `Sphinx specific
+markup constructs`_.
+
+.. _reStructuredText Primer: http://www.sphinx-doc.org/en/stable/rest.html
+.. _Sphinx specific markup constructs: http://www.sphinx-doc.org/en/stable/markup/index.html
+
+Specific guidelines for the kernel documentation
+------------------------------------------------
+
+Here are some specific guidelines for the kernel documentation:
+
+* Please don't go overboard with reStructuredText markup. Keep it
+  simple. For the most part the documentation should be plain text with
+  just enough consistency in formatting that it can be converted to
+  other formats.
+
+* Please keep the formatting changes minimal when converting existing
+  documentation to reStructuredText.
+
+* Also update the content, not just the formatting, when converting
+  documentation.
+
+* Please stick to this order of heading adornments:
+
+  1. ``=`` with overline for document title::
+
+       ==============
+       Document title
+       ==============
+
+  2. ``=`` for chapters::
+
+       Chapters
+       ========
+
+  3. ``-`` for sections::
+
+       Section
+       -------
+
+  4. ``~`` for subsections::
+
+       Subsection
+       ~~~~~~~~~~
+
+  Although RST doesn't mandate a specific order ("Rather than imposing a fixed
+  number and order of section title adornment styles, the order enforced will be
+  the order as encountered."), having the higher levels the same overall makes
+  it easier to follow the documents.
+
+* For inserting fixed width text blocks (for code examples, use case
+  examples, etc.), use ``::`` for anything that doesn't really benefit
+  from syntax highlighting, especially short snippets. Use
+  ``.. code-block:: <language>`` for longer code blocks that benefit
+  from highlighting. For a short snippet of code embedded in the text, use \`\`.
+
+
+the C domain
+------------
+
+The **Sphinx C Domain** (name c) is suited for documentation of C API. E.g. a
+function prototype:
+
+.. code-block:: rst
+
+    .. c:function:: int ioctl( int fd, int request )
+
+The C domain of the kernel-doc has some additional features. E.g. you can
+*rename* the reference name of a function with a common name like ``open`` or
+``ioctl``:
+
+.. code-block:: rst
+
+     .. c:function:: int ioctl( int fd, int request )
+        :name: VIDIOC_LOG_STATUS
+
+The func-name (e.g. ioctl) remains in the output but the ref-name changed from
+``ioctl`` to ``VIDIOC_LOG_STATUS``. The index entry for this function is also
+changed to ``VIDIOC_LOG_STATUS``.
+
+Please note that there is no need to use ``c:func:`` to generate cross
+references to function documentation.  Due to some Sphinx extension magic,
+the documentation build system will automatically turn a reference to
+``function()`` into a cross reference if an index entry for the given
+function name exists.  If you see ``c:func:`` use in a kernel document,
+please feel free to remove it.
+
+Tables
+------
+
+ReStructuredText provides several options for table syntax. Kernel style for
+tables is to prefer *simple table* syntax or *grid table* syntax. See the
+`reStructuredText user reference for table syntax`_ for more details.
+
+.. _reStructuredText user reference for table syntax:
+   https://docutils.sourceforge.io/docs/user/rst/quickref.html#tables
+
+list tables
+~~~~~~~~~~~
+
+The list-table formats can be useful for tables that are not easily laid
+out in the usual Sphinx ASCII-art formats.  These formats are nearly
+impossible for readers of the plain-text documents to understand, though,
+and should be avoided in the absence of a strong justification for their
+use.
+
+The ``flat-table`` is a double-stage list similar to the ``list-table`` with
+some additional features:
+
+* column-span: with the role ``cspan`` a cell can be extended through
+  additional columns
+
+* row-span: with the role ``rspan`` a cell can be extended through
+  additional rows
+
+* auto span rightmost cell of a table row over the missing cells on the right
+  side of that table-row.  With Option ``:fill-cells:`` this behavior can
+  changed from *auto span* to *auto fill*, which automatically inserts (empty)
+  cells instead of spanning the last cell.
+
+options:
+
+* ``:header-rows:``   [int] count of header rows
+* ``:stub-columns:``  [int] count of stub columns
+* ``:widths:``        [[int] [int] ... ] widths of columns
+* ``:fill-cells:``    instead of auto-spanning missing cells, insert missing cells
+
+roles:
+
+* ``:cspan:`` [int] additional columns (*morecols*)
+* ``:rspan:`` [int] additional rows (*morerows*)
+
+The example below shows how to use this markup.  The first level of the staged
+list is the *table-row*. In the *table-row* there is only one markup allowed,
+the list of the cells in this *table-row*. Exceptions are *comments* ( ``..`` )
+and *targets* (e.g. a ref to ``:ref:`last row <last row>``` / :ref:`last row
+<last row>`).
+
+.. code-block:: rst
+
+   .. flat-table:: table title
+      :widths: 2 1 1 3
+
+      * - head col 1
+        - head col 2
+        - head col 3
+        - head col 4
+
+      * - row 1
+        - field 1.1
+        - field 1.2 with autospan
+
+      * - row 2
+        - field 2.1
+        - :rspan:`1` :cspan:`1` field 2.2 - 3.3
+
+      * .. _`last row`:
+
+        - row 3
+
+Rendered as:
+
+   .. flat-table:: table title
+      :widths: 2 1 1 3
+
+      * - head col 1
+        - head col 2
+        - head col 3
+        - head col 4
+
+      * - row 1
+        - field 1.1
+        - field 1.2 with autospan
+
+      * - row 2
+        - field 2.1
+        - :rspan:`1` :cspan:`1` field 2.2 - 3.3
+
+      * .. _`last row`:
+
+        - row 3
+
+Cross-referencing
+-----------------
+
+Cross-referencing from one documentation page to another can be done simply by
+writing the path to the document file, no special syntax required. The path can
+be either absolute or relative. For absolute paths, start it with
+"Documentation/". For example, to cross-reference to this page, all the
+following are valid options, depending on the current document's directory (note
+that the ``.rst`` extension is required)::
+
+    See Documentation/doc-guide/sphinx.rst. This always works.
+    Take a look at sphinx.rst, which is at this same directory.
+    Read ../sphinx.rst, which is one directory above.
+
+If you want the link to have a different rendered text other than the document's
+title, you need to use Sphinx's ``doc`` role. For example::
+
+    See :doc:`my custom link text for document sphinx <sphinx>`.
+
+For most use cases, the former is preferred, as it is cleaner and more suited
+for people reading the source files. If you come across a ``:doc:`` usage that
+isn't adding any value, please feel free to convert it to just the document
+path.
+
+For information on cross-referencing to kernel-doc functions or types, see
+Documentation/doc-guide/kernel-doc.rst.
+
+.. _sphinx_kfigure:
+
+Figures & Images
+================
+
+If you want to add an image, you should use the ``kernel-figure`` and
+``kernel-image`` directives. E.g. to insert a figure with a scalable
+image format, use SVG (:ref:`svg_image_example`)::
+
+    .. kernel-figure::  svg_image.svg
+       :alt:    simple SVG image
+
+       SVG image example
+
+.. _svg_image_example:
+
+.. kernel-figure::  svg_image.svg
+   :alt:    simple SVG image
+
+   SVG image example
+
+The kernel figure (and image) directive supports **DOT** formatted files, see
+
+* DOT: http://graphviz.org/pdf/dotguide.pdf
+* Graphviz: http://www.graphviz.org/content/dot-language
+
+A simple example (:ref:`hello_dot_file`)::
+
+  .. kernel-figure::  hello.dot
+     :alt:    hello world
+
+     DOT's hello world example
+
+.. _hello_dot_file:
+
+.. kernel-figure::  hello.dot
+   :alt:    hello world
+
+   DOT's hello world example
+
+Embedded *render* markups (or languages) like Graphviz's **DOT** are provided by the
+``kernel-render`` directives.::
+
+  .. kernel-render:: DOT
+     :alt: foobar digraph
+     :caption: Embedded **DOT** (Graphviz) code
+
+     digraph foo {
+      "bar" -> "baz";
+     }
+
+How this will be rendered depends on the installed tools. If Graphviz is
+installed, you will see a vector image. If not, the raw markup is inserted as
+*literal-block* (:ref:`hello_dot_render`).
+
+.. _hello_dot_render:
+
+.. kernel-render:: DOT
+   :alt: foobar digraph
+   :caption: Embedded **DOT** (Graphviz) code
+
+   digraph foo {
+      "bar" -> "baz";
+   }
+
+The *render* directive has all the options known from the *figure* directive,
+plus option ``caption``.  If ``caption`` has a value, a *figure* node is
+inserted. If not, an *image* node is inserted. A ``caption`` is also needed, if
+you want to refer to it (:ref:`hello_svg_render`).
+
+Embedded **SVG**::
+
+  .. kernel-render:: SVG
+     :caption: Embedded **SVG** markup
+     :alt: so-nw-arrow
+
+     <?xml version="1.0" encoding="UTF-8"?>
+     <svg xmlns="http://www.w3.org/2000/svg" version="1.1" ...>
+        ...
+     </svg>
+
+.. _hello_svg_render:
+
+.. kernel-render:: SVG
+   :caption: Embedded **SVG** markup
+   :alt: so-nw-arrow
+
+   <?xml version="1.0" encoding="UTF-8"?>
+   <svg xmlns="http://www.w3.org/2000/svg"
+     version="1.1" baseProfile="full" width="70px" height="40px" viewBox="0 0 700 400">
+   <line x1="180" y1="370" x2="500" y2="50" stroke="black" stroke-width="15px"/>
+   <polygon points="585 0 525 25 585 50" transform="rotate(135 525 25)"/>
+   </svg>
diff --git a/Documentation/doc-guide/svg_image.svg b/Documentation/doc-guide/svg_image.svg
new file mode 100644
index 0000000000..5405f85b81
--- /dev/null
+++ b/Documentation/doc-guide/svg_image.svg
@@ -0,0 +1,10 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- originate: https://commons.wikimedia.org/wiki/File:Variable_Resistor.svg -->
+<svg xmlns="http://www.w3.org/2000/svg"
+	version="1.1" baseProfile="full"
+	width="70px" height="40px" viewBox="0 0 700 400">
+	<line x1="0" y1="200" x2="700" y2="200" stroke="black" stroke-width="20px"/>
+	<rect x="100" y="100" width="500" height="200" fill="white" stroke="black" stroke-width="20px"/>
+	<line x1="180" y1="370" x2="500" y2="50" stroke="black" stroke-width="15px"/>
+	<polygon points="585 0 525 25 585 50" transform="rotate(135 525 25)"/>
+</svg>