drivers/gpu/drm/udl/udl_modeset.c - LeafOS-Devices/android_kernel_realme_mt6785 - Gitiles

 /*
  * 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>

  * This file is subject to the terms and conditions of the GNU General Public
  * License v2. See the file COPYING in the main directory of this archive for
  * more details.
  */

 #include <drm/drmP.h>
 #include <drm/drm_crtc.h>
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_plane_helper.h>
 #include "udl_drv.h"

 /*
  * 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);
 }

 /*
  * On/Off for driving the DisplayLink framebuffer to the display
  *  0x00 H and V sync on
  *  0x01 H and V sync off (screen blank but powered)
  *  0x07 DPMS powerdown (requires modeset to come back)
  */
 static char *udl_set_blank(char *buf, int dpms_mode)
 {
 	u8 reg;
 	switch (dpms_mode) {
 	case DRM_MODE_DPMS_OFF:
 		reg = 0x07;
 		break;
 	case DRM_MODE_DPMS_STANDBY:
 		reg = 0x05;
 		break;
 	case DRM_MODE_DPMS_SUSPEND:
 		reg = 0x01;
 		break;
 	case DRM_MODE_DPMS_ON:
 		reg = 0x00;
 		break;
 	}

 	return udl_set_register(buf, 0x1f, reg);
 }

 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 = dev->dev_private;
 	struct urb *urb;
 	char *buf;
 	int retval;

 	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_INFO("write mode info %d\n", udl->mode_buf_len);
 	return retval;
 }


 static void udl_crtc_dpms(struct drm_crtc *crtc, int mode)
 {
 	struct drm_device *dev = crtc->dev;
 	struct udl_device *udl = dev->dev_private;
 	int retval;

 	if (mode == DRM_MODE_DPMS_OFF) {
 		char *buf;
 		struct urb *urb;
 		urb = udl_get_urb(dev);
 		if (!urb)
 			return;

 		buf = (char *)urb->transfer_buffer;
 		buf = udl_vidreg_lock(buf);
 		buf = udl_set_blank(buf, mode);
 		buf = udl_vidreg_unlock(buf);

 		buf = udl_dummy_render(buf);
 		retval = udl_submit_urb(dev, urb, buf - (char *)
 					urb->transfer_buffer);
 	} else {
 		if (udl->mode_buf_len == 0) {
 			DRM_ERROR("Trying to enable DPMS with no mode\n");
 			return;
 		}
 		udl_crtc_write_mode_to_hw(crtc);
 	}

 }

 static bool udl_crtc_mode_fixup(struct drm_crtc *crtc,
 				  const struct drm_display_mode *mode,
 				  struct drm_display_mode *adjusted_mode)

 {
 	return true;
 }

 #if 0
 static int
 udl_pipe_set_base_atomic(struct drm_crtc *crtc, struct drm_framebuffer *fb,
 			   int x, int y, enum mode_set_atomic state)
 {
 	return 0;
 }

 static int
 udl_pipe_set_base(struct drm_crtc *crtc, int x, int y,
 		    struct drm_framebuffer *old_fb)
 {
 	return 0;
 }
 #endif

 static int udl_crtc_mode_set(struct drm_crtc *crtc,
 			       struct drm_display_mode *mode,
 			       struct drm_display_mode *adjusted_mode,
 			       int x, int y,
 			       struct drm_framebuffer *old_fb)

 {
 	struct drm_device *dev = crtc->dev;
 	struct udl_framebuffer *ufb = to_udl_fb(crtc->primary->fb);
 	struct udl_device *udl = dev->dev_private;
 	char *buf;
 	char *wrptr;
 	int color_depth = 0;

 	buf = (char *)udl->mode_buf;

 	/* for now we just clip 24 -> 16 - if we fix that fix this */
 	/*if  (crtc->fb->bits_per_pixel != 16)
 	  color_depth = 1; */

 	/* 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, adjusted_mode);
 	wrptr = udl_set_blank(wrptr, DRM_MODE_DPMS_ON);
 	wrptr = udl_vidreg_unlock(wrptr);

 	wrptr = udl_dummy_render(wrptr);

 	if (old_fb) {
 		struct udl_framebuffer *uold_fb = to_udl_fb(old_fb);
 		uold_fb->active_16 = false;
 	}
 	ufb->active_16 = true;
 	udl->mode_buf_len = wrptr - buf;

 	/* damage all of it */
 	udl_handle_damage(ufb, 0, 0, ufb->base.width, ufb->base.height);
 	return 0;
 }


 static void udl_crtc_disable(struct drm_crtc *crtc)
 {
 	udl_crtc_dpms(crtc, DRM_MODE_DPMS_OFF);
 }

 static void udl_crtc_destroy(struct drm_crtc *crtc)
 {
 	drm_crtc_cleanup(crtc);
 	kfree(crtc);
 }

 static int udl_crtc_page_flip(struct drm_crtc *crtc,
 			      struct drm_framebuffer *fb,
 			      struct drm_pending_vblank_event *event,
 			      uint32_t page_flip_flags)
 {
 	struct udl_framebuffer *ufb = to_udl_fb(fb);
 	struct drm_device *dev = crtc->dev;
 	unsigned long flags;

 	struct drm_framebuffer *old_fb = crtc->primary->fb;
 	if (old_fb) {
 		struct udl_framebuffer *uold_fb = to_udl_fb(old_fb);
 		uold_fb->active_16 = false;
 	}
 	ufb->active_16 = true;

 	udl_handle_damage(ufb, 0, 0, fb->width, fb->height);

 	spin_lock_irqsave(&dev->event_lock, flags);
 	if (event)
 		drm_send_vblank_event(dev, 0, event);
 	spin_unlock_irqrestore(&dev->event_lock, flags);
 	crtc->primary->fb = fb;

 	return 0;
 }

 static void udl_crtc_prepare(struct drm_crtc *crtc)
 {
 }

 static void udl_crtc_commit(struct drm_crtc *crtc)
 {
 	udl_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
 }

 static const struct drm_crtc_helper_funcs udl_helper_funcs = {
 	.dpms = udl_crtc_dpms,
 	.mode_fixup = udl_crtc_mode_fixup,
 	.mode_set = udl_crtc_mode_set,
 	.prepare = udl_crtc_prepare,
 	.commit = udl_crtc_commit,
 	.disable = udl_crtc_disable,
 };

 static const struct drm_crtc_funcs udl_crtc_funcs = {
 	.set_config = drm_crtc_helper_set_config,
 	.destroy = udl_crtc_destroy,
 	.page_flip = udl_crtc_page_flip,
 };

 static int udl_crtc_init(struct drm_device *dev)
 {
 	struct drm_crtc *crtc;

 	crtc = kzalloc(sizeof(struct drm_crtc) + sizeof(struct drm_connector *), GFP_KERNEL);
 	if (crtc == NULL)
 		return -ENOMEM;

 	drm_crtc_init(dev, crtc, &udl_crtc_funcs);
 	drm_crtc_helper_add(crtc, &udl_helper_funcs);

 	return 0;
 }

 static const struct drm_mode_config_funcs udl_mode_funcs = {
 	.fb_create = udl_fb_user_fb_create,
 	.output_poll_changed = NULL,
 };

 int udl_modeset_init(struct drm_device *dev)
 {
 	struct drm_encoder *encoder;
 	drm_mode_config_init(dev);

 	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 = 24;

 	dev->mode_config.funcs = &udl_mode_funcs;

 	drm_mode_create_dirty_info_property(dev);

 	udl_crtc_init(dev);

 	encoder = udl_encoder_init(dev);

 	udl_connector_init(dev, encoder);

 	return 0;
 }

 void udl_modeset_cleanup(struct drm_device *dev)
 {
 	drm_mode_config_cleanup(dev);
 }
	/*
	* 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>

	* This file is subject to the terms and conditions of the GNU General Public
	* License v2. See the file COPYING in the main directory of this archive for
	* more details.
	*/

	#include <drm/drmP.h>
	#include <drm/drm_crtc.h>
	#include <drm/drm_crtc_helper.h>
	#include <drm/drm_plane_helper.h>
	#include "udl_drv.h"

	/*
	* 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);
	}

	/*
	* On/Off for driving the DisplayLink framebuffer to the display
	* 0x00 H and V sync on
	* 0x01 H and V sync off (screen blank but powered)
	* 0x07 DPMS powerdown (requires modeset to come back)
	*/
	static char udl_set_blank(char buf, int dpms_mode)
	{
	u8 reg;
	switch (dpms_mode) {
	case DRM_MODE_DPMS_OFF:
	reg = 0x07;
	break;
	case DRM_MODE_DPMS_STANDBY:
	reg = 0x05;
	break;
	case DRM_MODE_DPMS_SUSPEND:
	reg = 0x01;
	break;
	case DRM_MODE_DPMS_ON:
	reg = 0x00;
	break;
	}

	return udl_set_register(buf, 0x1f, reg);
	}

	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 = dev->dev_private;
	struct urb *urb;
	char *buf;
	int retval;

	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_INFO("write mode info %d\n", udl->mode_buf_len);
	return retval;
	}


	static void udl_crtc_dpms(struct drm_crtc *crtc, int mode)
	{
	struct drm_device *dev = crtc->dev;
	struct udl_device *udl = dev->dev_private;
	int retval;

	if (mode == DRM_MODE_DPMS_OFF) {
	char *buf;
	struct urb *urb;
	urb = udl_get_urb(dev);
	if (!urb)
	return;

	buf = (char *)urb->transfer_buffer;
	buf = udl_vidreg_lock(buf);
	buf = udl_set_blank(buf, mode);
	buf = udl_vidreg_unlock(buf);

	buf = udl_dummy_render(buf);
	retval = udl_submit_urb(dev, urb, buf - (char *)
	urb->transfer_buffer);
	} else {
	if (udl->mode_buf_len == 0) {
	DRM_ERROR("Trying to enable DPMS with no mode\n");
	return;
	}
	udl_crtc_write_mode_to_hw(crtc);
	}

	}

	static bool udl_crtc_mode_fixup(struct drm_crtc *crtc,
	const struct drm_display_mode *mode,
	struct drm_display_mode *adjusted_mode)

	{
	return true;
	}

	#if 0
	static int
	udl_pipe_set_base_atomic(struct drm_crtc crtc, struct drm_framebuffer fb,
	int x, int y, enum mode_set_atomic state)
	{
	return 0;
	}

	static int
	udl_pipe_set_base(struct drm_crtc *crtc, int x, int y,
	struct drm_framebuffer *old_fb)
	{
	return 0;
	}
	#endif

	static int udl_crtc_mode_set(struct drm_crtc *crtc,
	struct drm_display_mode *mode,
	struct drm_display_mode *adjusted_mode,
	int x, int y,
	struct drm_framebuffer *old_fb)

	{
	struct drm_device *dev = crtc->dev;
	struct udl_framebuffer *ufb = to_udl_fb(crtc->primary->fb);
	struct udl_device *udl = dev->dev_private;
	char *buf;
	char *wrptr;
	int color_depth = 0;

	buf = (char *)udl->mode_buf;

	/* for now we just clip 24 -> 16 - if we fix that fix this */
	/*if (crtc->fb->bits_per_pixel != 16)
	color_depth = 1; */

	/* 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, adjusted_mode);
	wrptr = udl_set_blank(wrptr, DRM_MODE_DPMS_ON);
	wrptr = udl_vidreg_unlock(wrptr);

	wrptr = udl_dummy_render(wrptr);

	if (old_fb) {
	struct udl_framebuffer *uold_fb = to_udl_fb(old_fb);
	uold_fb->active_16 = false;
	}
	ufb->active_16 = true;
	udl->mode_buf_len = wrptr - buf;

	/* damage all of it */
	udl_handle_damage(ufb, 0, 0, ufb->base.width, ufb->base.height);
	return 0;
	}


	static void udl_crtc_disable(struct drm_crtc *crtc)
	{
	udl_crtc_dpms(crtc, DRM_MODE_DPMS_OFF);
	}

	static void udl_crtc_destroy(struct drm_crtc *crtc)
	{
	drm_crtc_cleanup(crtc);
	kfree(crtc);
	}

	static int udl_crtc_page_flip(struct drm_crtc *crtc,
	struct drm_framebuffer *fb,
	struct drm_pending_vblank_event *event,
	uint32_t page_flip_flags)
	{
	struct udl_framebuffer *ufb = to_udl_fb(fb);
	struct drm_device *dev = crtc->dev;
	unsigned long flags;

	struct drm_framebuffer *old_fb = crtc->primary->fb;
	if (old_fb) {
	struct udl_framebuffer *uold_fb = to_udl_fb(old_fb);
	uold_fb->active_16 = false;
	}
	ufb->active_16 = true;

	udl_handle_damage(ufb, 0, 0, fb->width, fb->height);

	spin_lock_irqsave(&dev->event_lock, flags);
	if (event)
	drm_send_vblank_event(dev, 0, event);
	spin_unlock_irqrestore(&dev->event_lock, flags);
	crtc->primary->fb = fb;

	return 0;
	}

	static void udl_crtc_prepare(struct drm_crtc *crtc)
	{
	}

	static void udl_crtc_commit(struct drm_crtc *crtc)
	{
	udl_crtc_dpms(crtc, DRM_MODE_DPMS_ON);
	}

	static const struct drm_crtc_helper_funcs udl_helper_funcs = {
	.dpms = udl_crtc_dpms,
	.mode_fixup = udl_crtc_mode_fixup,
	.mode_set = udl_crtc_mode_set,
	.prepare = udl_crtc_prepare,
	.commit = udl_crtc_commit,
	.disable = udl_crtc_disable,
	};

	static const struct drm_crtc_funcs udl_crtc_funcs = {
	.set_config = drm_crtc_helper_set_config,
	.destroy = udl_crtc_destroy,
	.page_flip = udl_crtc_page_flip,
	};

	static int udl_crtc_init(struct drm_device *dev)
	{
	struct drm_crtc *crtc;

	crtc = kzalloc(sizeof(struct drm_crtc) + sizeof(struct drm_connector *), GFP_KERNEL);
	if (crtc == NULL)
	return -ENOMEM;

	drm_crtc_init(dev, crtc, &udl_crtc_funcs);
	drm_crtc_helper_add(crtc, &udl_helper_funcs);

	return 0;
	}

	static const struct drm_mode_config_funcs udl_mode_funcs = {
	.fb_create = udl_fb_user_fb_create,
	.output_poll_changed = NULL,
	};

	int udl_modeset_init(struct drm_device *dev)
	{
	struct drm_encoder *encoder;
	drm_mode_config_init(dev);

	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 = 24;

	dev->mode_config.funcs = &udl_mode_funcs;

	drm_mode_create_dirty_info_property(dev);

	udl_crtc_init(dev);

	encoder = udl_encoder_init(dev);

	udl_connector_init(dev, encoder);

	return 0;
	}

	void udl_modeset_cleanup(struct drm_device *dev)
	{
	drm_mode_config_cleanup(dev);
	}