Adding upstream version 6.6.15.upstream/6.6.15

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

1 files changed, 29 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-devices-state_synced b/Documentation/ABI/testing/sysfs-devices-state_synced
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index 0000000000..c64636ddac
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+What:		/sys/devices/.../state_synced
+Date:		May 2020
+Contact:	Saravana Kannan <saravanak@google.com>
+Description:
+		The /sys/devices/.../state_synced attribute is only present for
+		devices whose bus types or driver provides the .sync_state()
+		callback. The number read from it (0 or 1) reflects the value
+		of the device's 'state_synced' field. A value of 0 means the
+		.sync_state() callback hasn't been called yet. A value of 1
+		means the .sync_state() callback has been called.
+
+		Generally, if a device has sync_state() support and has some of
+		the resources it provides enabled at the time the kernel starts
+		(Eg: enabled by hardware reset or bootloader or anything that
+		run before the kernel starts), then it'll keep those resources
+		enabled and in a state that's compatible with the state they
+		were in at the start of the kernel. The device will stop doing
+		this only when the sync_state() callback has been called --
+		which happens only when all its consumer devices are registered
+		and have probed successfully. Resources that were left disabled
+		at the time the kernel starts are not affected or limited in
+		any way by sync_state() callbacks.
+
+		Writing "1" to this file will force a call to the device's
+		sync_state() function if it hasn't been called already. The
+		sync_state() call happens independent of the state of the
+		consumer devices.
+
+