Adding upstream version 5.10.209.upstream/5.10.209upstream

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

9 files changed, 1541 insertions, 0 deletions

diff --git a/drivers/gpu/drm/udl/Kconfig b/drivers/gpu/drm/udl/Kconfig
new file mode 100644
index 000000000..1f497d8f1
--- /dev/null
+++ b/drivers/gpu/drm/udl/Kconfig
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0-only
+config DRM_UDL
+	tristate "DisplayLink"
+	depends on DRM
+	depends on USB
+	depends on USB_ARCH_HAS_HCD
+	select DRM_GEM_SHMEM_HELPER
+	select DRM_KMS_HELPER
+	help
+	  This is a KMS driver for the USB displaylink video adapters.
+	  Say M/Y to add support for these devices via drm/kms interfaces.
diff --git a/drivers/gpu/drm/udl/Makefile b/drivers/gpu/drm/udl/Makefile
new file mode 100644
index 000000000..24d61f61d
--- /dev/null
+++ b/drivers/gpu/drm/udl/Makefile
@@ -0,0 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0-only
+udl-y := udl_drv.o udl_modeset.o udl_connector.o udl_main.o udl_transfer.o
+
+obj-$(CONFIG_DRM_UDL) := udl.o
diff --git a/drivers/gpu/drm/udl/udl_connector.c b/drivers/gpu/drm/udl/udl_connector.c
new file mode 100644
index 000000000..aac41a809
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_connector.c
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat
+ * based in parts on udlfb.c:
+ * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+ * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+ * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+ */
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_probe_helper.h>
+
+#include "udl_connector.h"
+#include "udl_drv.h"
+
+static int udl_get_edid_block(void *data, u8 *buf, unsigned int block,
+			       size_t len)
+{
+	int ret, i;
+	u8 *read_buff;
+	struct udl_device *udl = data;
+
+	read_buff = kmalloc(2, GFP_KERNEL);
+	if (!read_buff)
+		return -1;
+
+	for (i = 0; i < len; i++) {
+		int bval = (i + block * EDID_LENGTH) << 8;
+		ret = usb_control_msg(udl->udev,
+				      usb_rcvctrlpipe(udl->udev, 0),
+					  (0x02), (0x80 | (0x02 << 5)), bval,
+					  0xA1, read_buff, 2, 1000);
+		if (ret < 1) {
+			DRM_ERROR("Read EDID byte %d failed err %x\n", i, ret);
+			kfree(read_buff);
+			return -1;
+		}
+		buf[i] = read_buff[1];
+	}
+
+	kfree(read_buff);
+	return 0;
+}
+
+static int udl_get_modes(struct drm_connector *connector)
+{
+	struct udl_drm_connector *udl_connector =
+					container_of(connector,
+					struct udl_drm_connector,
+					connector);
+
+	drm_connector_update_edid_property(connector, udl_connector->edid);
+	if (udl_connector->edid)
+		return drm_add_edid_modes(connector, udl_connector->edid);
+	return 0;
+}
+
+static enum drm_mode_status udl_mode_valid(struct drm_connector *connector,
+			  struct drm_display_mode *mode)
+{
+	struct udl_device *udl = to_udl(connector->dev);
+	if (!udl->sku_pixel_limit)
+		return 0;
+
+	if (mode->vdisplay * mode->hdisplay > udl->sku_pixel_limit)
+		return MODE_VIRTUAL_Y;
+
+	return 0;
+}
+
+static enum drm_connector_status
+udl_detect(struct drm_connector *connector, bool force)
+{
+	struct udl_device *udl = to_udl(connector->dev);
+	struct udl_drm_connector *udl_connector =
+					container_of(connector,
+					struct udl_drm_connector,
+					connector);
+
+	/* cleanup previous edid */
+	if (udl_connector->edid != NULL) {
+		kfree(udl_connector->edid);
+		udl_connector->edid = NULL;
+	}
+
+	udl_connector->edid = drm_do_get_edid(connector, udl_get_edid_block, udl);
+	if (!udl_connector->edid)
+		return connector_status_disconnected;
+
+	return connector_status_connected;
+}
+
+static void udl_connector_destroy(struct drm_connector *connector)
+{
+	struct udl_drm_connector *udl_connector =
+					container_of(connector,
+					struct udl_drm_connector,
+					connector);
+
+	drm_connector_cleanup(connector);
+	kfree(udl_connector->edid);
+	kfree(connector);
+}
+
+static const struct drm_connector_helper_funcs udl_connector_helper_funcs = {
+	.get_modes = udl_get_modes,
+	.mode_valid = udl_mode_valid,
+};
+
+static const struct drm_connector_funcs udl_connector_funcs = {
+	.reset = drm_atomic_helper_connector_reset,
+	.detect = udl_detect,
+	.fill_modes = drm_helper_probe_single_connector_modes,
+	.destroy = udl_connector_destroy,
+	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+	.atomic_destroy_state   = drm_atomic_helper_connector_destroy_state,
+};
+
+struct drm_connector *udl_connector_init(struct drm_device *dev)
+{
+	struct udl_drm_connector *udl_connector;
+	struct drm_connector *connector;
+
+	udl_connector = kzalloc(sizeof(struct udl_drm_connector), GFP_KERNEL);
+	if (!udl_connector)
+		return ERR_PTR(-ENOMEM);
+
+	connector = &udl_connector->connector;
+	drm_connector_init(dev, connector, &udl_connector_funcs,
+			   DRM_MODE_CONNECTOR_DVII);
+	drm_connector_helper_add(connector, &udl_connector_helper_funcs);
+
+	connector->polled = DRM_CONNECTOR_POLL_HPD |
+		DRM_CONNECTOR_POLL_CONNECT | DRM_CONNECTOR_POLL_DISCONNECT;
+
+	return connector;
+}
diff --git a/drivers/gpu/drm/udl/udl_connector.h b/drivers/gpu/drm/udl/udl_connector.h
new file mode 100644
index 000000000..7f2d392df
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_connector.h
@@ -0,0 +1,15 @@
+#ifndef __UDL_CONNECTOR_H__
+#define __UDL_CONNECTOR_H__
+
+#include <drm/drm_crtc.h>
+
+struct edid;
+
+struct udl_drm_connector {
+	struct drm_connector connector;
+	/* last udl_detect edid */
+	struct edid *edid;
+};
+
+
+#endif //__UDL_CONNECTOR_H__
diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
new file mode 100644
index 000000000..bcf32d188
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_drv.c
@@ -0,0 +1,151 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat
+ */
+
+#include <linux/module.h>
+
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_file.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_ioctl.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_print.h>
+
+#include "udl_drv.h"
+
+static int udl_usb_suspend(struct usb_interface *interface,
+			   pm_message_t message)
+{
+	struct drm_device *dev = usb_get_intfdata(interface);
+
+	return drm_mode_config_helper_suspend(dev);
+}
+
+static int udl_usb_resume(struct usb_interface *interface)
+{
+	struct drm_device *dev = usb_get_intfdata(interface);
+
+	return drm_mode_config_helper_resume(dev);
+}
+
+/*
+ * FIXME: Dma-buf sharing requires DMA support by the importing device.
+ *        This function is a workaround to make USB devices work as well.
+ *        See todo.rst for how to fix the issue in the dma-buf framework.
+ */
+static struct drm_gem_object *udl_driver_gem_prime_import(struct drm_device *dev,
+							  struct dma_buf *dma_buf)
+{
+	struct udl_device *udl = to_udl(dev);
+
+	if (!udl->dmadev)
+		return ERR_PTR(-ENODEV);
+
+	return drm_gem_prime_import_dev(dev, dma_buf, udl->dmadev);
+}
+
+DEFINE_DRM_GEM_FOPS(udl_driver_fops);
+
+static struct drm_driver driver = {
+	.driver_features = DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
+
+	/* GEM hooks */
+	.gem_create_object = drm_gem_shmem_create_object_cached,
+
+	.fops = &udl_driver_fops,
+	DRM_GEM_SHMEM_DRIVER_OPS,
+	.gem_prime_import = udl_driver_gem_prime_import,
+
+	.name = DRIVER_NAME,
+	.desc = DRIVER_DESC,
+	.date = DRIVER_DATE,
+	.major = DRIVER_MAJOR,
+	.minor = DRIVER_MINOR,
+	.patchlevel = DRIVER_PATCHLEVEL,
+};
+
+static struct udl_device *udl_driver_create(struct usb_interface *interface)
+{
+	struct usb_device *udev = interface_to_usbdev(interface);
+	struct udl_device *udl;
+	int r;
+
+	udl = devm_drm_dev_alloc(&interface->dev, &driver,
+				 struct udl_device, drm);
+	if (IS_ERR(udl))
+		return udl;
+
+	udl->udev = udev;
+
+	r = udl_init(udl);
+	if (r)
+		return ERR_PTR(r);
+
+	usb_set_intfdata(interface, udl);
+
+	return udl;
+}
+
+static int udl_usb_probe(struct usb_interface *interface,
+			 const struct usb_device_id *id)
+{
+	int r;
+	struct udl_device *udl;
+
+	udl = udl_driver_create(interface);
+	if (IS_ERR(udl))
+		return PTR_ERR(udl);
+
+	r = drm_dev_register(&udl->drm, 0);
+	if (r)
+		return r;
+
+	DRM_INFO("Initialized udl on minor %d\n", udl->drm.primary->index);
+
+	drm_fbdev_generic_setup(&udl->drm, 0);
+
+	return 0;
+}
+
+static void udl_usb_disconnect(struct usb_interface *interface)
+{
+	struct drm_device *dev = usb_get_intfdata(interface);
+
+	drm_kms_helper_poll_fini(dev);
+	udl_drop_usb(dev);
+	drm_dev_unplug(dev);
+}
+
+/*
+ * There are many DisplayLink-based graphics products, all with unique PIDs.
+ * So we match on DisplayLink's VID + Vendor-Defined Interface Class (0xff)
+ * We also require a match on SubClass (0x00) and Protocol (0x00),
+ * which is compatible with all known USB 2.0 era graphics chips and firmware,
+ * but allows DisplayLink to increment those for any future incompatible chips
+ */
+static const struct usb_device_id id_table[] = {
+	{.idVendor = 0x17e9, .bInterfaceClass = 0xff,
+	 .bInterfaceSubClass = 0x00,
+	 .bInterfaceProtocol = 0x00,
+	 .match_flags = USB_DEVICE_ID_MATCH_VENDOR |
+			USB_DEVICE_ID_MATCH_INT_CLASS |
+			USB_DEVICE_ID_MATCH_INT_SUBCLASS |
+			USB_DEVICE_ID_MATCH_INT_PROTOCOL,},
+	{},
+};
+MODULE_DEVICE_TABLE(usb, id_table);
+
+static struct usb_driver udl_driver = {
+	.name = "udl",
+	.probe = udl_usb_probe,
+	.disconnect = udl_usb_disconnect,
+	.suspend = udl_usb_suspend,
+	.resume = udl_usb_resume,
+	.id_table = id_table,
+};
+module_usb_driver(udl_driver);
+MODULE_LICENSE("GPL");
diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
new file mode 100644
index 000000000..8aab14871
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_drv.h
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2012 Red Hat
+ *
+ * based in parts on udlfb.c:
+ * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+ * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+ * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+ */
+
+#ifndef UDL_DRV_H
+#define UDL_DRV_H
+
+#include <linux/mm_types.h>
+#include <linux/usb.h>
+
+#include <drm/drm_device.h>
+#include <drm/drm_framebuffer.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_simple_kms_helper.h>
+
+struct drm_mode_create_dumb;
+
+#define DRIVER_NAME		"udl"
+#define DRIVER_DESC		"DisplayLink"
+#define DRIVER_DATE		"20120220"
+
+#define DRIVER_MAJOR		0
+#define DRIVER_MINOR		0
+#define DRIVER_PATCHLEVEL	1
+
+struct udl_device;
+
+struct urb_node {
+	struct list_head entry;
+	struct udl_device *dev;
+	struct delayed_work release_urb_work;
+	struct urb *urb;
+};
+
+struct urb_list {
+	struct list_head list;
+	spinlock_t lock;
+	struct semaphore limit_sem;
+	int available;
+	int count;
+	size_t size;
+};
+
+struct udl_device {
+	struct drm_device drm;
+	struct device *dev;
+	struct device *dmadev;
+	struct usb_device *udev;
+
+	struct drm_simple_display_pipe display_pipe;
+
+	struct mutex gem_lock;
+
+	int sku_pixel_limit;
+
+	struct urb_list urbs;
+
+	char mode_buf[1024];
+	uint32_t mode_buf_len;
+};
+
+#define to_udl(x) container_of(x, struct udl_device, drm)
+
+/* modeset */
+int udl_modeset_init(struct drm_device *dev);
+struct drm_connector *udl_connector_init(struct drm_device *dev);
+
+struct urb *udl_get_urb(struct drm_device *dev);
+
+int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len);
+void udl_urb_completion(struct urb *urb);
+
+int udl_init(struct udl_device *udl);
+
+int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr,
+		     const char *front, char **urb_buf_ptr,
+		     u32 byte_offset, u32 device_byte_offset, u32 byte_width);
+
+int udl_drop_usb(struct drm_device *dev);
+
+#define CMD_WRITE_RAW8   "\xAF\x60" /**< 8 bit raw write command. */
+#define CMD_WRITE_RL8    "\xAF\x61" /**< 8 bit run length command. */
+#define CMD_WRITE_COPY8  "\xAF\x62" /**< 8 bit copy command. */
+#define CMD_WRITE_RLX8   "\xAF\x63" /**< 8 bit extended run length command. */
+
+#define CMD_WRITE_RAW16  "\xAF\x68" /**< 16 bit raw write command. */
+#define CMD_WRITE_RL16   "\xAF\x69" /**< 16 bit run length command. */
+#define CMD_WRITE_COPY16 "\xAF\x6A" /**< 16 bit copy command. */
+#define CMD_WRITE_RLX16  "\xAF\x6B" /**< 16 bit extended run length command. */
+
+/* On/Off for driving the DisplayLink framebuffer to the display */
+#define UDL_REG_BLANK_MODE		0x1f
+
+#define UDL_BLANK_MODE_ON		0x00 /* hsync and vsync on, visible */
+#define UDL_BLANK_MODE_BLANKED		0x01 /* hsync and vsync on, blanked */
+#define UDL_BLANK_MODE_VSYNC_OFF	0x03 /* vsync off, blanked */
+#define UDL_BLANK_MODE_HSYNC_OFF	0x05 /* hsync off, blanked */
+#define UDL_BLANK_MODE_POWERDOWN	0x07 /* powered off; requires modeset */
+
+#endif
diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
new file mode 100644
index 000000000..5f1d3891e
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_main.c
@@ -0,0 +1,363 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat
+ *
+ * based in parts on udlfb.c:
+ * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+ * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+ * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+ */
+
+#include <drm/drm.h>
+#include <drm/drm_print.h>
+#include <drm/drm_probe_helper.h>
+
+#include "udl_drv.h"
+
+/* -BULK_SIZE as per usb-skeleton. Can we get full page and avoid overhead? */
+#define BULK_SIZE 512
+
+#define NR_USB_REQUEST_CHANNEL 0x12
+
+#define MAX_TRANSFER (PAGE_SIZE*16 - BULK_SIZE)
+#define WRITES_IN_FLIGHT (4)
+#define MAX_VENDOR_DESCRIPTOR_SIZE 256
+
+#define GET_URB_TIMEOUT	HZ
+#define FREE_URB_TIMEOUT (HZ*2)
+
+static int udl_parse_vendor_descriptor(struct drm_device *dev,
+				       struct usb_device *usbdev)
+{
+	struct udl_device *udl = to_udl(dev);
+	char *desc;
+	char *buf;
+	char *desc_end;
+
+	u8 total_len = 0;
+
+	buf = kzalloc(MAX_VENDOR_DESCRIPTOR_SIZE, GFP_KERNEL);
+	if (!buf)
+		return false;
+	desc = buf;
+
+	total_len = usb_get_descriptor(usbdev, 0x5f, /* vendor specific */
+				    0, desc, MAX_VENDOR_DESCRIPTOR_SIZE);
+	if (total_len > 5) {
+		DRM_INFO("vendor descriptor length:%x data:%11ph\n",
+			total_len, desc);
+
+		if ((desc[0] != total_len) || /* descriptor length */
+		    (desc[1] != 0x5f) ||   /* vendor descriptor type */
+		    (desc[2] != 0x01) ||   /* version (2 bytes) */
+		    (desc[3] != 0x00) ||
+		    (desc[4] != total_len - 2)) /* length after type */
+			goto unrecognized;
+
+		desc_end = desc + total_len;
+		desc += 5; /* the fixed header we've already parsed */
+
+		while (desc < desc_end) {
+			u8 length;
+			u16 key;
+
+			key = le16_to_cpu(*((u16 *) desc));
+			desc += sizeof(u16);
+			length = *desc;
+			desc++;
+
+			switch (key) {
+			case 0x0200: { /* max_area */
+				u32 max_area;
+				max_area = le32_to_cpu(*((u32 *)desc));
+				DRM_DEBUG("DL chip limited to %d pixel modes\n",
+					max_area);
+				udl->sku_pixel_limit = max_area;
+				break;
+			}
+			default:
+				break;
+			}
+			desc += length;
+		}
+	}
+
+	goto success;
+
+unrecognized:
+	/* allow udlfb to load for now even if firmware unrecognized */
+	DRM_ERROR("Unrecognized vendor firmware descriptor\n");
+
+success:
+	kfree(buf);
+	return true;
+}
+
+/*
+ * Need to ensure a channel is selected before submitting URBs
+ */
+static int udl_select_std_channel(struct udl_device *udl)
+{
+	int ret;
+	static const u8 set_def_chn[] = {0x57, 0xCD, 0xDC, 0xA7,
+					 0x1C, 0x88, 0x5E, 0x15,
+					 0x60, 0xFE, 0xC6, 0x97,
+					 0x16, 0x3D, 0x47, 0xF2};
+	void *sendbuf;
+
+	sendbuf = kmemdup(set_def_chn, sizeof(set_def_chn), GFP_KERNEL);
+	if (!sendbuf)
+		return -ENOMEM;
+
+	ret = usb_control_msg(udl->udev,
+			      usb_sndctrlpipe(udl->udev, 0),
+			      NR_USB_REQUEST_CHANNEL,
+			      (USB_DIR_OUT | USB_TYPE_VENDOR), 0, 0,
+			      sendbuf, sizeof(set_def_chn),
+			      USB_CTRL_SET_TIMEOUT);
+	kfree(sendbuf);
+	return ret < 0 ? ret : 0;
+}
+
+static void udl_release_urb_work(struct work_struct *work)
+{
+	struct urb_node *unode = container_of(work, struct urb_node,
+					      release_urb_work.work);
+
+	up(&unode->dev->urbs.limit_sem);
+}
+
+void udl_urb_completion(struct urb *urb)
+{
+	struct urb_node *unode = urb->context;
+	struct udl_device *udl = unode->dev;
+	unsigned long flags;
+
+	/* sync/async unlink faults aren't errors */
+	if (urb->status) {
+		if (!(urb->status == -ENOENT ||
+		    urb->status == -ECONNRESET ||
+		    urb->status == -ESHUTDOWN)) {
+			DRM_ERROR("%s - nonzero write bulk status received: %d\n",
+				__func__, urb->status);
+		}
+	}
+
+	urb->transfer_buffer_length = udl->urbs.size; /* reset to actual */
+
+	spin_lock_irqsave(&udl->urbs.lock, flags);
+	list_add_tail(&unode->entry, &udl->urbs.list);
+	udl->urbs.available++;
+	spin_unlock_irqrestore(&udl->urbs.lock, flags);
+
+#if 0
+	/*
+	 * When using fb_defio, we deadlock if up() is called
+	 * while another is waiting. So queue to another process.
+	 */
+	if (fb_defio)
+		schedule_delayed_work(&unode->release_urb_work, 0);
+	else
+#endif
+		up(&udl->urbs.limit_sem);
+}
+
+static void udl_free_urb_list(struct drm_device *dev)
+{
+	struct udl_device *udl = to_udl(dev);
+	int count = udl->urbs.count;
+	struct list_head *node;
+	struct urb_node *unode;
+	struct urb *urb;
+
+	DRM_DEBUG("Waiting for completes and freeing all render urbs\n");
+
+	/* keep waiting and freeing, until we've got 'em all */
+	while (count--) {
+		down(&udl->urbs.limit_sem);
+
+		spin_lock_irq(&udl->urbs.lock);
+
+		node = udl->urbs.list.next; /* have reserved one with sem */
+		list_del_init(node);
+
+		spin_unlock_irq(&udl->urbs.lock);
+
+		unode = list_entry(node, struct urb_node, entry);
+		urb = unode->urb;
+
+		/* Free each separately allocated piece */
+		usb_free_coherent(urb->dev, udl->urbs.size,
+				  urb->transfer_buffer, urb->transfer_dma);
+		usb_free_urb(urb);
+		kfree(node);
+	}
+	udl->urbs.count = 0;
+}
+
+static int udl_alloc_urb_list(struct drm_device *dev, int count, size_t size)
+{
+	struct udl_device *udl = to_udl(dev);
+	struct urb *urb;
+	struct urb_node *unode;
+	char *buf;
+	size_t wanted_size = count * size;
+
+	spin_lock_init(&udl->urbs.lock);
+
+retry:
+	udl->urbs.size = size;
+	INIT_LIST_HEAD(&udl->urbs.list);
+
+	sema_init(&udl->urbs.limit_sem, 0);
+	udl->urbs.count = 0;
+	udl->urbs.available = 0;
+
+	while (udl->urbs.count * size < wanted_size) {
+		unode = kzalloc(sizeof(struct urb_node), GFP_KERNEL);
+		if (!unode)
+			break;
+		unode->dev = udl;
+
+		INIT_DELAYED_WORK(&unode->release_urb_work,
+			  udl_release_urb_work);
+
+		urb = usb_alloc_urb(0, GFP_KERNEL);
+		if (!urb) {
+			kfree(unode);
+			break;
+		}
+		unode->urb = urb;
+
+		buf = usb_alloc_coherent(udl->udev, size, GFP_KERNEL,
+					 &urb->transfer_dma);
+		if (!buf) {
+			kfree(unode);
+			usb_free_urb(urb);
+			if (size > PAGE_SIZE) {
+				size /= 2;
+				udl_free_urb_list(dev);
+				goto retry;
+			}
+			break;
+		}
+
+		/* urb->transfer_buffer_length set to actual before submit */
+		usb_fill_bulk_urb(urb, udl->udev, usb_sndbulkpipe(udl->udev, 1),
+			buf, size, udl_urb_completion, unode);
+		urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
+
+		list_add_tail(&unode->entry, &udl->urbs.list);
+
+		up(&udl->urbs.limit_sem);
+		udl->urbs.count++;
+		udl->urbs.available++;
+	}
+
+	DRM_DEBUG("allocated %d %d byte urbs\n", udl->urbs.count, (int) size);
+
+	return udl->urbs.count;
+}
+
+struct urb *udl_get_urb(struct drm_device *dev)
+{
+	struct udl_device *udl = to_udl(dev);
+	int ret = 0;
+	struct list_head *entry;
+	struct urb_node *unode;
+	struct urb *urb = NULL;
+
+	/* Wait for an in-flight buffer to complete and get re-queued */
+	ret = down_timeout(&udl->urbs.limit_sem, GET_URB_TIMEOUT);
+	if (ret) {
+		DRM_INFO("wait for urb interrupted: %x available: %d\n",
+		       ret, udl->urbs.available);
+		goto error;
+	}
+
+	spin_lock_irq(&udl->urbs.lock);
+
+	BUG_ON(list_empty(&udl->urbs.list)); /* reserved one with limit_sem */
+	entry = udl->urbs.list.next;
+	list_del_init(entry);
+	udl->urbs.available--;
+
+	spin_unlock_irq(&udl->urbs.lock);
+
+	unode = list_entry(entry, struct urb_node, entry);
+	urb = unode->urb;
+
+error:
+	return urb;
+}
+
+int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len)
+{
+	struct udl_device *udl = to_udl(dev);
+	int ret;
+
+	BUG_ON(len > udl->urbs.size);
+
+	urb->transfer_buffer_length = len; /* set to actual payload len */
+	ret = usb_submit_urb(urb, GFP_ATOMIC);
+	if (ret) {
+		udl_urb_completion(urb); /* because no one else will */
+		DRM_ERROR("usb_submit_urb error %x\n", ret);
+	}
+	return ret;
+}
+
+int udl_init(struct udl_device *udl)
+{
+	struct drm_device *dev = &udl->drm;
+	int ret = -ENOMEM;
+
+	DRM_DEBUG("\n");
+
+	udl->dmadev = usb_intf_get_dma_device(to_usb_interface(dev->dev));
+	if (!udl->dmadev)
+		drm_warn(dev, "buffer sharing not supported"); /* not an error */
+
+	mutex_init(&udl->gem_lock);
+
+	if (!udl_parse_vendor_descriptor(dev, udl->udev)) {
+		ret = -ENODEV;
+		DRM_ERROR("firmware not recognized. Assume incompatible device\n");
+		goto err;
+	}
+
+	if (udl_select_std_channel(udl))
+		DRM_ERROR("Selecting channel failed\n");
+
+	if (!udl_alloc_urb_list(dev, WRITES_IN_FLIGHT, MAX_TRANSFER)) {
+		DRM_ERROR("udl_alloc_urb_list failed\n");
+		goto err;
+	}
+
+	DRM_DEBUG("\n");
+	ret = udl_modeset_init(dev);
+	if (ret)
+		goto err;
+
+	drm_kms_helper_poll_init(dev);
+
+	return 0;
+
+err:
+	if (udl->urbs.count)
+		udl_free_urb_list(dev);
+	put_device(udl->dmadev);
+	DRM_ERROR("%d\n", ret);
+	return ret;
+}
+
+int udl_drop_usb(struct drm_device *dev)
+{
+	struct udl_device *udl = to_udl(dev);
+
+	udl_free_urb_list(dev);
+	put_device(udl->dmadev);
+	udl->dmadev = NULL;
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/udl/udl_modeset.c b/drivers/gpu/drm/udl/udl_modeset.c
new file mode 100644
index 000000000..209b5ceba
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_modeset.c
@@ -0,0 +1,501 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat
+ *
+ * based in parts on udlfb.c:
+ * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+ * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+ * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+
+ */
+
+#include <linux/dma-buf.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_vblank.h>
+
+#include "udl_drv.h"
+
+#define UDL_COLOR_DEPTH_16BPP	0
+
+/*
+ * All DisplayLink bulk operations start with 0xAF, followed by specific code
+ * All operations are written to buffers which then later get sent to device
+ */
+static char *udl_set_register(char *buf, u8 reg, u8 val)
+{
+	*buf++ = 0xAF;
+	*buf++ = 0x20;
+	*buf++ = reg;
+	*buf++ = val;
+	return buf;
+}
+
+static char *udl_vidreg_lock(char *buf)
+{
+	return udl_set_register(buf, 0xFF, 0x00);
+}
+
+static char *udl_vidreg_unlock(char *buf)
+{
+	return udl_set_register(buf, 0xFF, 0xFF);
+}
+
+static char *udl_set_blank_mode(char *buf, u8 mode)
+{
+	return udl_set_register(buf, UDL_REG_BLANK_MODE, mode);
+}
+
+static char *udl_set_color_depth(char *buf, u8 selection)
+{
+	return udl_set_register(buf, 0x00, selection);
+}
+
+static char *udl_set_base16bpp(char *wrptr, u32 base)
+{
+	/* the base pointer is 16 bits wide, 0x20 is hi byte. */
+	wrptr = udl_set_register(wrptr, 0x20, base >> 16);
+	wrptr = udl_set_register(wrptr, 0x21, base >> 8);
+	return udl_set_register(wrptr, 0x22, base);
+}
+
+/*
+ * DisplayLink HW has separate 16bpp and 8bpp framebuffers.
+ * In 24bpp modes, the low 323 RGB bits go in the 8bpp framebuffer
+ */
+static char *udl_set_base8bpp(char *wrptr, u32 base)
+{
+	wrptr = udl_set_register(wrptr, 0x26, base >> 16);
+	wrptr = udl_set_register(wrptr, 0x27, base >> 8);
+	return udl_set_register(wrptr, 0x28, base);
+}
+
+static char *udl_set_register_16(char *wrptr, u8 reg, u16 value)
+{
+	wrptr = udl_set_register(wrptr, reg, value >> 8);
+	return udl_set_register(wrptr, reg+1, value);
+}
+
+/*
+ * This is kind of weird because the controller takes some
+ * register values in a different byte order than other registers.
+ */
+static char *udl_set_register_16be(char *wrptr, u8 reg, u16 value)
+{
+	wrptr = udl_set_register(wrptr, reg, value);
+	return udl_set_register(wrptr, reg+1, value >> 8);
+}
+
+/*
+ * LFSR is linear feedback shift register. The reason we have this is
+ * because the display controller needs to minimize the clock depth of
+ * various counters used in the display path. So this code reverses the
+ * provided value into the lfsr16 value by counting backwards to get
+ * the value that needs to be set in the hardware comparator to get the
+ * same actual count. This makes sense once you read above a couple of
+ * times and think about it from a hardware perspective.
+ */
+static u16 udl_lfsr16(u16 actual_count)
+{
+	u32 lv = 0xFFFF; /* This is the lfsr value that the hw starts with */
+
+	while (actual_count--) {
+		lv =	 ((lv << 1) |
+			(((lv >> 15) ^ (lv >> 4) ^ (lv >> 2) ^ (lv >> 1)) & 1))
+			& 0xFFFF;
+	}
+
+	return (u16) lv;
+}
+
+/*
+ * This does LFSR conversion on the value that is to be written.
+ * See LFSR explanation above for more detail.
+ */
+static char *udl_set_register_lfsr16(char *wrptr, u8 reg, u16 value)
+{
+	return udl_set_register_16(wrptr, reg, udl_lfsr16(value));
+}
+
+/*
+ * This takes a standard fbdev screeninfo struct and all of its monitor mode
+ * details and converts them into the DisplayLink equivalent register commands.
+  ERR(vreg(dev,               0x00, (color_depth == 16) ? 0 : 1));
+  ERR(vreg_lfsr16(dev,        0x01, xDisplayStart));
+  ERR(vreg_lfsr16(dev,        0x03, xDisplayEnd));
+  ERR(vreg_lfsr16(dev,        0x05, yDisplayStart));
+  ERR(vreg_lfsr16(dev,        0x07, yDisplayEnd));
+  ERR(vreg_lfsr16(dev,        0x09, xEndCount));
+  ERR(vreg_lfsr16(dev,        0x0B, hSyncStart));
+  ERR(vreg_lfsr16(dev,        0x0D, hSyncEnd));
+  ERR(vreg_big_endian(dev,    0x0F, hPixels));
+  ERR(vreg_lfsr16(dev,        0x11, yEndCount));
+  ERR(vreg_lfsr16(dev,        0x13, vSyncStart));
+  ERR(vreg_lfsr16(dev,        0x15, vSyncEnd));
+  ERR(vreg_big_endian(dev,    0x17, vPixels));
+  ERR(vreg_little_endian(dev, 0x1B, pixelClock5KHz));
+
+  ERR(vreg(dev,               0x1F, 0));
+
+  ERR(vbuf(dev, WRITE_VIDREG_UNLOCK, DSIZEOF(WRITE_VIDREG_UNLOCK)));
+ */
+static char *udl_set_vid_cmds(char *wrptr, struct drm_display_mode *mode)
+{
+	u16 xds, yds;
+	u16 xde, yde;
+	u16 yec;
+
+	/* x display start */
+	xds = mode->crtc_htotal - mode->crtc_hsync_start;
+	wrptr = udl_set_register_lfsr16(wrptr, 0x01, xds);
+	/* x display end */
+	xde = xds + mode->crtc_hdisplay;
+	wrptr = udl_set_register_lfsr16(wrptr, 0x03, xde);
+
+	/* y display start */
+	yds = mode->crtc_vtotal - mode->crtc_vsync_start;
+	wrptr = udl_set_register_lfsr16(wrptr, 0x05, yds);
+	/* y display end */
+	yde = yds + mode->crtc_vdisplay;
+	wrptr = udl_set_register_lfsr16(wrptr, 0x07, yde);
+
+	/* x end count is active + blanking - 1 */
+	wrptr = udl_set_register_lfsr16(wrptr, 0x09,
+					mode->crtc_htotal - 1);
+
+	/* libdlo hardcodes hsync start to 1 */
+	wrptr = udl_set_register_lfsr16(wrptr, 0x0B, 1);
+
+	/* hsync end is width of sync pulse + 1 */
+	wrptr = udl_set_register_lfsr16(wrptr, 0x0D,
+					mode->crtc_hsync_end - mode->crtc_hsync_start + 1);
+
+	/* hpixels is active pixels */
+	wrptr = udl_set_register_16(wrptr, 0x0F, mode->hdisplay);
+
+	/* yendcount is vertical active + vertical blanking */
+	yec = mode->crtc_vtotal;
+	wrptr = udl_set_register_lfsr16(wrptr, 0x11, yec);
+
+	/* libdlo hardcodes vsync start to 0 */
+	wrptr = udl_set_register_lfsr16(wrptr, 0x13, 0);
+
+	/* vsync end is width of vsync pulse */
+	wrptr = udl_set_register_lfsr16(wrptr, 0x15, mode->crtc_vsync_end - mode->crtc_vsync_start);
+
+	/* vpixels is active pixels */
+	wrptr = udl_set_register_16(wrptr, 0x17, mode->crtc_vdisplay);
+
+	wrptr = udl_set_register_16be(wrptr, 0x1B,
+				      mode->clock / 5);
+
+	return wrptr;
+}
+
+static char *udl_dummy_render(char *wrptr)
+{
+	*wrptr++ = 0xAF;
+	*wrptr++ = 0x6A; /* copy */
+	*wrptr++ = 0x00; /* from addr */
+	*wrptr++ = 0x00;
+	*wrptr++ = 0x00;
+	*wrptr++ = 0x01; /* one pixel */
+	*wrptr++ = 0x00; /* to address */
+	*wrptr++ = 0x00;
+	*wrptr++ = 0x00;
+	return wrptr;
+}
+
+static int udl_crtc_write_mode_to_hw(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct udl_device *udl = to_udl(dev);
+	struct urb *urb;
+	char *buf;
+	int retval;
+
+	if (udl->mode_buf_len == 0) {
+		DRM_ERROR("No mode set\n");
+		return -EINVAL;
+	}
+
+	urb = udl_get_urb(dev);
+	if (!urb)
+		return -ENOMEM;
+
+	buf = (char *)urb->transfer_buffer;
+
+	memcpy(buf, udl->mode_buf, udl->mode_buf_len);
+	retval = udl_submit_urb(dev, urb, udl->mode_buf_len);
+	DRM_DEBUG("write mode info %d\n", udl->mode_buf_len);
+	return retval;
+}
+
+static long udl_log_cpp(unsigned int cpp)
+{
+	if (WARN_ON(!is_power_of_2(cpp)))
+		return -EINVAL;
+	return __ffs(cpp);
+}
+
+static int udl_aligned_damage_clip(struct drm_rect *clip, int x, int y,
+				   int width, int height)
+{
+	int x1, x2;
+
+	if (WARN_ON_ONCE(x < 0) ||
+	    WARN_ON_ONCE(y < 0) ||
+	    WARN_ON_ONCE(width < 0) ||
+	    WARN_ON_ONCE(height < 0))
+		return -EINVAL;
+
+	x1 = ALIGN_DOWN(x, sizeof(unsigned long));
+	x2 = ALIGN(width + (x - x1), sizeof(unsigned long)) + x1;
+
+	clip->x1 = x1;
+	clip->y1 = y;
+	clip->x2 = x2;
+	clip->y2 = y + height;
+
+	return 0;
+}
+
+static int udl_handle_damage(struct drm_framebuffer *fb, int x, int y,
+			     int width, int height)
+{
+	struct drm_device *dev = fb->dev;
+	struct dma_buf_attachment *import_attach = fb->obj[0]->import_attach;
+	int i, ret, tmp_ret;
+	char *cmd;
+	struct urb *urb;
+	struct drm_rect clip;
+	int log_bpp;
+	void *vaddr;
+
+	ret = udl_log_cpp(fb->format->cpp[0]);
+	if (ret < 0)
+		return ret;
+	log_bpp = ret;
+
+	ret = udl_aligned_damage_clip(&clip, x, y, width, height);
+	if (ret)
+		return ret;
+	else if ((clip.x2 > fb->width) || (clip.y2 > fb->height))
+		return -EINVAL;
+
+	if (import_attach) {
+		ret = dma_buf_begin_cpu_access(import_attach->dmabuf,
+					       DMA_FROM_DEVICE);
+		if (ret)
+			return ret;
+	}
+
+	vaddr = drm_gem_shmem_vmap(fb->obj[0]);
+	if (IS_ERR(vaddr)) {
+		DRM_ERROR("failed to vmap fb\n");
+		goto out_dma_buf_end_cpu_access;
+	}
+
+	urb = udl_get_urb(dev);
+	if (!urb) {
+		ret = -ENOMEM;
+		goto out_drm_gem_shmem_vunmap;
+	}
+	cmd = urb->transfer_buffer;
+
+	for (i = clip.y1; i < clip.y2; i++) {
+		const int line_offset = fb->pitches[0] * i;
+		const int byte_offset = line_offset + (clip.x1 << log_bpp);
+		const int dev_byte_offset = (fb->width * i + clip.x1) << log_bpp;
+		const int byte_width = (clip.x2 - clip.x1) << log_bpp;
+		ret = udl_render_hline(dev, log_bpp, &urb, (char *)vaddr,
+				       &cmd, byte_offset, dev_byte_offset,
+				       byte_width);
+		if (ret)
+			goto out_drm_gem_shmem_vunmap;
+	}
+
+	if (cmd > (char *)urb->transfer_buffer) {
+		/* Send partial buffer remaining before exiting */
+		int len;
+		if (cmd < (char *)urb->transfer_buffer + urb->transfer_buffer_length)
+			*cmd++ = 0xAF;
+		len = cmd - (char *)urb->transfer_buffer;
+		ret = udl_submit_urb(dev, urb, len);
+	} else {
+		udl_urb_completion(urb);
+	}
+
+	ret = 0;
+
+out_drm_gem_shmem_vunmap:
+	drm_gem_shmem_vunmap(fb->obj[0], vaddr);
+out_dma_buf_end_cpu_access:
+	if (import_attach) {
+		tmp_ret = dma_buf_end_cpu_access(import_attach->dmabuf,
+						 DMA_FROM_DEVICE);
+		if (tmp_ret && !ret)
+			ret = tmp_ret; /* only update ret if not set yet */
+	}
+
+	return ret;
+}
+
+/*
+ * Simple display pipeline
+ */
+
+static const uint32_t udl_simple_display_pipe_formats[] = {
+	DRM_FORMAT_RGB565,
+	DRM_FORMAT_XRGB8888,
+};
+
+static enum drm_mode_status
+udl_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
+				   const struct drm_display_mode *mode)
+{
+	return MODE_OK;
+}
+
+static void
+udl_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
+			       struct drm_crtc_state *crtc_state,
+			       struct drm_plane_state *plane_state)
+{
+	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_device *dev = crtc->dev;
+	struct drm_framebuffer *fb = plane_state->fb;
+	struct udl_device *udl = to_udl(dev);
+	struct drm_display_mode *mode = &crtc_state->mode;
+	char *buf;
+	char *wrptr;
+	int color_depth = UDL_COLOR_DEPTH_16BPP;
+
+	buf = (char *)udl->mode_buf;
+
+	/* This first section has to do with setting the base address on the
+	 * controller associated with the display. There are 2 base
+	 * pointers, currently, we only use the 16 bpp segment.
+	 */
+	wrptr = udl_vidreg_lock(buf);
+	wrptr = udl_set_color_depth(wrptr, color_depth);
+	/* set base for 16bpp segment to 0 */
+	wrptr = udl_set_base16bpp(wrptr, 0);
+	/* set base for 8bpp segment to end of fb */
+	wrptr = udl_set_base8bpp(wrptr, 2 * mode->vdisplay * mode->hdisplay);
+
+	wrptr = udl_set_vid_cmds(wrptr, mode);
+	wrptr = udl_set_blank_mode(wrptr, UDL_BLANK_MODE_ON);
+	wrptr = udl_vidreg_unlock(wrptr);
+
+	wrptr = udl_dummy_render(wrptr);
+
+	udl->mode_buf_len = wrptr - buf;
+
+	udl_handle_damage(fb, 0, 0, fb->width, fb->height);
+
+	/* enable display */
+	udl_crtc_write_mode_to_hw(crtc);
+}
+
+static void
+udl_simple_display_pipe_disable(struct drm_simple_display_pipe *pipe)
+{
+	struct drm_crtc *crtc = &pipe->crtc;
+	struct drm_device *dev = crtc->dev;
+	struct urb *urb;
+	char *buf;
+
+	urb = udl_get_urb(dev);
+	if (!urb)
+		return;
+
+	buf = (char *)urb->transfer_buffer;
+	buf = udl_vidreg_lock(buf);
+	buf = udl_set_blank_mode(buf, UDL_BLANK_MODE_POWERDOWN);
+	buf = udl_vidreg_unlock(buf);
+	buf = udl_dummy_render(buf);
+
+	udl_submit_urb(dev, urb, buf - (char *)urb->transfer_buffer);
+}
+
+static void
+udl_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
+			       struct drm_plane_state *old_plane_state)
+{
+	struct drm_plane_state *state = pipe->plane.state;
+	struct drm_framebuffer *fb = state->fb;
+	struct drm_rect rect;
+
+	if (!fb)
+		return;
+
+	if (drm_atomic_helper_damage_merged(old_plane_state, state, &rect))
+		udl_handle_damage(fb, rect.x1, rect.y1, rect.x2 - rect.x1,
+				  rect.y2 - rect.y1);
+}
+
+static const
+struct drm_simple_display_pipe_funcs udl_simple_display_pipe_funcs = {
+	.mode_valid = udl_simple_display_pipe_mode_valid,
+	.enable = udl_simple_display_pipe_enable,
+	.disable = udl_simple_display_pipe_disable,
+	.update = udl_simple_display_pipe_update,
+	.prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+/*
+ * Modesetting
+ */
+
+static const struct drm_mode_config_funcs udl_mode_funcs = {
+	.fb_create = drm_gem_fb_create_with_dirty,
+	.atomic_check  = drm_atomic_helper_check,
+	.atomic_commit = drm_atomic_helper_commit,
+};
+
+int udl_modeset_init(struct drm_device *dev)
+{
+	size_t format_count = ARRAY_SIZE(udl_simple_display_pipe_formats);
+	struct udl_device *udl = to_udl(dev);
+	struct drm_connector *connector;
+	int ret;
+
+	ret = drmm_mode_config_init(dev);
+	if (ret)
+		return ret;
+
+	dev->mode_config.min_width = 640;
+	dev->mode_config.min_height = 480;
+
+	dev->mode_config.max_width = 2048;
+	dev->mode_config.max_height = 2048;
+
+	dev->mode_config.prefer_shadow = 0;
+	dev->mode_config.preferred_depth = 16;
+
+	dev->mode_config.funcs = &udl_mode_funcs;
+
+	connector = udl_connector_init(dev);
+	if (IS_ERR(connector))
+		return PTR_ERR(connector);
+
+	format_count = ARRAY_SIZE(udl_simple_display_pipe_formats);
+
+	ret = drm_simple_display_pipe_init(dev, &udl->display_pipe,
+					   &udl_simple_display_pipe_funcs,
+					   udl_simple_display_pipe_formats,
+					   format_count, NULL, connector);
+	if (ret)
+		return ret;
+
+	drm_mode_config_reset(dev);
+
+	return 0;
+}
diff --git a/drivers/gpu/drm/udl/udl_transfer.c b/drivers/gpu/drm/udl/udl_transfer.c
new file mode 100644
index 000000000..971927669
--- /dev/null
+++ b/drivers/gpu/drm/udl/udl_transfer.c
@@ -0,0 +1,252 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2012 Red Hat
+ * based in parts on udlfb.c:
+ * Copyright (C) 2009 Roberto De Ioris <roberto@unbit.it>
+ * Copyright (C) 2009 Jaya Kumar <jayakumar.lkml@gmail.com>
+ * Copyright (C) 2009 Bernie Thompson <bernie@plugable.com>
+ */
+
+#include <asm/unaligned.h>
+
+#include "udl_drv.h"
+
+#define MAX_CMD_PIXELS		255
+
+#define RLX_HEADER_BYTES	7
+#define MIN_RLX_PIX_BYTES       4
+#define MIN_RLX_CMD_BYTES	(RLX_HEADER_BYTES + MIN_RLX_PIX_BYTES)
+
+#define RLE_HEADER_BYTES	6
+#define MIN_RLE_PIX_BYTES	3
+#define MIN_RLE_CMD_BYTES	(RLE_HEADER_BYTES + MIN_RLE_PIX_BYTES)
+
+#define RAW_HEADER_BYTES	6
+#define MIN_RAW_PIX_BYTES	2
+#define MIN_RAW_CMD_BYTES	(RAW_HEADER_BYTES + MIN_RAW_PIX_BYTES)
+
+/*
+ * Trims identical data from front and back of line
+ * Sets new front buffer address and width
+ * And returns byte count of identical pixels
+ * Assumes CPU natural alignment (unsigned long)
+ * for back and front buffer ptrs and width
+ */
+#if 0
+static int udl_trim_hline(const u8 *bback, const u8 **bfront, int *width_bytes)
+{
+	int j, k;
+	const unsigned long *back = (const unsigned long *) bback;
+	const unsigned long *front = (const unsigned long *) *bfront;
+	const int width = *width_bytes / sizeof(unsigned long);
+	int identical = width;
+	int start = width;
+	int end = width;
+
+	for (j = 0; j < width; j++) {
+		if (back[j] != front[j]) {
+			start = j;
+			break;
+		}
+	}
+
+	for (k = width - 1; k > j; k--) {
+		if (back[k] != front[k]) {
+			end = k+1;
+			break;
+		}
+	}
+
+	identical = start + (width - end);
+	*bfront = (u8 *) &front[start];
+	*width_bytes = (end - start) * sizeof(unsigned long);
+
+	return identical * sizeof(unsigned long);
+}
+#endif
+
+static inline u16 pixel32_to_be16(const uint32_t pixel)
+{
+	return (((pixel >> 3) & 0x001f) |
+		((pixel >> 5) & 0x07e0) |
+		((pixel >> 8) & 0xf800));
+}
+
+static inline u16 get_pixel_val16(const uint8_t *pixel, int log_bpp)
+{
+	u16 pixel_val16;
+	if (log_bpp == 1)
+		pixel_val16 = *(const uint16_t *)pixel;
+	else
+		pixel_val16 = pixel32_to_be16(*(const uint32_t *)pixel);
+	return pixel_val16;
+}
+
+/*
+ * Render a command stream for an encoded horizontal line segment of pixels.
+ *
+ * A command buffer holds several commands.
+ * It always begins with a fresh command header
+ * (the protocol doesn't require this, but we enforce it to allow
+ * multiple buffers to be potentially encoded and sent in parallel).
+ * A single command encodes one contiguous horizontal line of pixels
+ *
+ * The function relies on the client to do all allocation, so that
+ * rendering can be done directly to output buffers (e.g. USB URBs).
+ * The function fills the supplied command buffer, providing information
+ * on where it left off, so the client may call in again with additional
+ * buffers if the line will take several buffers to complete.
+ *
+ * A single command can transmit a maximum of 256 pixels,
+ * regardless of the compression ratio (protocol design limit).
+ * To the hardware, 0 for a size byte means 256
+ *
+ * Rather than 256 pixel commands which are either rl or raw encoded,
+ * the rlx command simply assumes alternating raw and rl spans within one cmd.
+ * This has a slightly larger header overhead, but produces more even results.
+ * It also processes all data (read and write) in a single pass.
+ * Performance benchmarks of common cases show it having just slightly better
+ * compression than 256 pixel raw or rle commands, with similar CPU consumpion.
+ * But for very rl friendly data, will compress not quite as well.
+ */
+static void udl_compress_hline16(
+	const u8 **pixel_start_ptr,
+	const u8 *const pixel_end,
+	uint32_t *device_address_ptr,
+	uint8_t **command_buffer_ptr,
+	const uint8_t *const cmd_buffer_end, int log_bpp)
+{
+	const int bpp = 1 << log_bpp;
+	const u8 *pixel = *pixel_start_ptr;
+	uint32_t dev_addr  = *device_address_ptr;
+	uint8_t *cmd = *command_buffer_ptr;
+
+	while ((pixel_end > pixel) &&
+	       (cmd_buffer_end - MIN_RLX_CMD_BYTES > cmd)) {
+		uint8_t *raw_pixels_count_byte = NULL;
+		uint8_t *cmd_pixels_count_byte = NULL;
+		const u8 *raw_pixel_start = NULL;
+		const u8 *cmd_pixel_start, *cmd_pixel_end = NULL;
+		uint16_t pixel_val16;
+
+		*cmd++ = 0xaf;
+		*cmd++ = 0x6b;
+		*cmd++ = (uint8_t) ((dev_addr >> 16) & 0xFF);
+		*cmd++ = (uint8_t) ((dev_addr >> 8) & 0xFF);
+		*cmd++ = (uint8_t) ((dev_addr) & 0xFF);
+
+		cmd_pixels_count_byte = cmd++; /*  we'll know this later */
+		cmd_pixel_start = pixel;
+
+		raw_pixels_count_byte = cmd++; /*  we'll know this later */
+		raw_pixel_start = pixel;
+
+		cmd_pixel_end = pixel + (min3(MAX_CMD_PIXELS + 1UL,
+					(unsigned long)(pixel_end - pixel) >> log_bpp,
+					(unsigned long)(cmd_buffer_end - 1 - cmd) / 2) << log_bpp);
+
+		pixel_val16 = get_pixel_val16(pixel, log_bpp);
+
+		while (pixel < cmd_pixel_end) {
+			const u8 *const start = pixel;
+			const uint16_t repeating_pixel_val16 = pixel_val16;
+
+			put_unaligned_be16(pixel_val16, cmd);
+
+			cmd += 2;
+			pixel += bpp;
+
+			while (pixel < cmd_pixel_end) {
+				pixel_val16 = get_pixel_val16(pixel, log_bpp);
+				if (pixel_val16 != repeating_pixel_val16)
+					break;
+				pixel += bpp;
+			}
+
+			if (unlikely(pixel > start + bpp)) {
+				/* go back and fill in raw pixel count */
+				*raw_pixels_count_byte = (((start -
+						raw_pixel_start) >> log_bpp) + 1) & 0xFF;
+
+				/* immediately after raw data is repeat byte */
+				*cmd++ = (((pixel - start) >> log_bpp) - 1) & 0xFF;
+
+				/* Then start another raw pixel span */
+				raw_pixel_start = pixel;
+				raw_pixels_count_byte = cmd++;
+			}
+		}
+
+		if (pixel > raw_pixel_start) {
+			/* finalize last RAW span */
+			*raw_pixels_count_byte = ((pixel - raw_pixel_start) >> log_bpp) & 0xFF;
+		} else {
+			/* undo unused byte */
+			cmd--;
+		}
+
+		*cmd_pixels_count_byte = ((pixel - cmd_pixel_start) >> log_bpp) & 0xFF;
+		dev_addr += ((pixel - cmd_pixel_start) >> log_bpp) * 2;
+	}
+
+	if (cmd_buffer_end <= MIN_RLX_CMD_BYTES + cmd) {
+		/* Fill leftover bytes with no-ops */
+		if (cmd_buffer_end > cmd)
+			memset(cmd, 0xAF, cmd_buffer_end - cmd);
+		cmd = (uint8_t *) cmd_buffer_end;
+	}
+
+	*command_buffer_ptr = cmd;
+	*pixel_start_ptr = pixel;
+	*device_address_ptr = dev_addr;
+
+	return;
+}
+
+/*
+ * There are 3 copies of every pixel: The front buffer that the fbdev
+ * client renders to, the actual framebuffer across the USB bus in hardware
+ * (that we can only write to, slowly, and can never read), and (optionally)
+ * our shadow copy that tracks what's been sent to that hardware buffer.
+ */
+int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr,
+		     const char *front, char **urb_buf_ptr,
+		     u32 byte_offset, u32 device_byte_offset,
+		     u32 byte_width)
+{
+	const u8 *line_start, *line_end, *next_pixel;
+	u32 base16 = 0 + (device_byte_offset >> log_bpp) * 2;
+	struct urb *urb = *urb_ptr;
+	u8 *cmd = *urb_buf_ptr;
+	u8 *cmd_end = (u8 *) urb->transfer_buffer + urb->transfer_buffer_length;
+
+	BUG_ON(!(log_bpp == 1 || log_bpp == 2));
+
+	line_start = (u8 *) (front + byte_offset);
+	next_pixel = line_start;
+	line_end = next_pixel + byte_width;
+
+	while (next_pixel < line_end) {
+
+		udl_compress_hline16(&next_pixel,
+			     line_end, &base16,
+			     (u8 **) &cmd, (u8 *) cmd_end, log_bpp);
+
+		if (cmd >= cmd_end) {
+			int len = cmd - (u8 *) urb->transfer_buffer;
+			int ret = udl_submit_urb(dev, urb, len);
+			if (ret)
+				return ret;
+			urb = udl_get_urb(dev);
+			if (!urb)
+				return -EAGAIN;
+			*urb_ptr = urb;
+			cmd = urb->transfer_buffer;
+			cmd_end = &cmd[urb->transfer_buffer_length];
+		}
+	}
+
+	*urb_buf_ptr = cmd;
+
+	return 0;
+}