drivers/gpu/drm/drm_format_helper.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0 or MIT
 /*
  * Copyright (C) 2016 Noralf Trønnes
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  */

 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/io.h>

 #include <drm/drm_format_helper.h>
 #include <drm/drm_framebuffer.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_rect.h>

 static unsigned int clip_offset(struct drm_rect *clip,
 				unsigned int pitch, unsigned int cpp)
 {
 	return clip->y1 * pitch + clip->x1 * cpp;
 }

 /**
  * drm_fb_memcpy - Copy clip buffer
  * @dst: Destination buffer
  * @vaddr: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  *
  * This function does not apply clipping on dst, i.e. the destination
  * is a small buffer containing the clip rect only.
  */
 void drm_fb_memcpy(void *dst, void *vaddr, struct drm_framebuffer *fb,
 		   struct drm_rect *clip)
 {
 	unsigned int cpp = fb->format->cpp[0];
 	size_t len = (clip->x2 - clip->x1) * cpp;
 	unsigned int y, lines = clip->y2 - clip->y1;

 	vaddr += clip_offset(clip, fb->pitches[0], cpp);
 	for (y = 0; y < lines; y++) {
 		memcpy(dst, vaddr, len);
 		vaddr += fb->pitches[0];
 		dst += len;
 	}
 }
 EXPORT_SYMBOL(drm_fb_memcpy);

 /**
  * drm_fb_memcpy_dstclip - Copy clip buffer
  * @dst: Destination buffer (iomem)
  * @vaddr: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  *
  * This function applies clipping on dst, i.e. the destination is a
  * full (iomem) framebuffer but only the clip rect content is copied over.
  */
 void drm_fb_memcpy_dstclip(void __iomem *dst, void *vaddr,
 			   struct drm_framebuffer *fb,
 			   struct drm_rect *clip)
 {
 	unsigned int cpp = fb->format->cpp[0];
 	unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
 	size_t len = (clip->x2 - clip->x1) * cpp;
 	unsigned int y, lines = clip->y2 - clip->y1;

 	vaddr += offset;
 	dst += offset;
 	for (y = 0; y < lines; y++) {
 		memcpy_toio(dst, vaddr, len);
 		vaddr += fb->pitches[0];
 		dst += fb->pitches[0];
 	}
 }
 EXPORT_SYMBOL(drm_fb_memcpy_dstclip);

 /**
  * drm_fb_swab - Swap bytes into clip buffer
  * @dst: Destination buffer
  * @src: Source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  * @cached: Source buffer is mapped cached (eg. not write-combined)
  *
  * If @cached is false a temporary buffer is used to cache one pixel line at a
  * time to speed up slow uncached reads.
  *
  * This function does not apply clipping on dst, i.e. the destination
  * is a small buffer containing the clip rect only.
  */
 void drm_fb_swab(void *dst, void *src, struct drm_framebuffer *fb,
 		 struct drm_rect *clip, bool cached)
 {
 	u8 cpp = fb->format->cpp[0];
 	size_t len = drm_rect_width(clip) * cpp;
 	u16 *src16, *dst16 = dst;
 	u32 *src32, *dst32 = dst;
 	unsigned int x, y;
 	void *buf = NULL;

 	if (WARN_ON_ONCE(cpp != 2 && cpp != 4))
 		return;

 	if (!cached)
 		buf = kmalloc(len, GFP_KERNEL);

 	src += clip_offset(clip, fb->pitches[0], cpp);

 	for (y = clip->y1; y < clip->y2; y++) {
 		if (buf) {
 			memcpy(buf, src, len);
 			src16 = buf;
 			src32 = buf;
 		} else {
 			src16 = src;
 			src32 = src;
 		}

 		for (x = clip->x1; x < clip->x2; x++) {
 			if (cpp == 4)
 				*dst32++ = swab32(*src32++);
 			else
 				*dst16++ = swab16(*src16++);
 		}

 		src += fb->pitches[0];
 	}

 	kfree(buf);
 }
 EXPORT_SYMBOL(drm_fb_swab);

 static void drm_fb_xrgb8888_to_rgb565_line(u16 *dbuf, u32 *sbuf,
 					   unsigned int pixels,
 					   bool swab)
 {
 	unsigned int x;
 	u16 val16;

 	for (x = 0; x < pixels; x++) {
 		val16 = ((sbuf[x] & 0x00F80000) >> 8) |
 			((sbuf[x] & 0x0000FC00) >> 5) |
 			((sbuf[x] & 0x000000F8) >> 3);
 		if (swab)
 			dbuf[x] = swab16(val16);
 		else
 			dbuf[x] = val16;
 	}
 }

 /**
  * drm_fb_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
  * @dst: RGB565 destination buffer
  * @vaddr: XRGB8888 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  * @swab: Swap bytes
  *
  * Drivers can use this function for RGB565 devices that don't natively
  * support XRGB8888.
  *
  * This function does not apply clipping on dst, i.e. the destination
  * is a small buffer containing the clip rect only.
  */
 void drm_fb_xrgb8888_to_rgb565(void *dst, void *vaddr,
 			       struct drm_framebuffer *fb,
 			       struct drm_rect *clip, bool swab)
 {
 	size_t linepixels = clip->x2 - clip->x1;
 	size_t src_len = linepixels * sizeof(u32);
 	size_t dst_len = linepixels * sizeof(u16);
 	unsigned y, lines = clip->y2 - clip->y1;
 	void *sbuf;

 	/*
 	 * The cma memory is write-combined so reads are uncached.
 	 * Speed up by fetching one line at a time.
 	 */
 	sbuf = kmalloc(src_len, GFP_KERNEL);
 	if (!sbuf)
 		return;

 	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
 	for (y = 0; y < lines; y++) {
 		memcpy(sbuf, vaddr, src_len);
 		drm_fb_xrgb8888_to_rgb565_line(dst, sbuf, linepixels, swab);
 		vaddr += fb->pitches[0];
 		dst += dst_len;
 	}

 	kfree(sbuf);
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565);

 /**
  * drm_fb_xrgb8888_to_rgb565_dstclip - Convert XRGB8888 to RGB565 clip buffer
  * @dst: RGB565 destination buffer (iomem)
  * @dst_pitch: destination buffer pitch
  * @vaddr: XRGB8888 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  * @swab: Swap bytes
  *
  * Drivers can use this function for RGB565 devices that don't natively
  * support XRGB8888.
  *
  * This function applies clipping on dst, i.e. the destination is a
  * full (iomem) framebuffer but only the clip rect content is copied over.
  */
 void drm_fb_xrgb8888_to_rgb565_dstclip(void __iomem *dst, unsigned int dst_pitch,
 				       void *vaddr, struct drm_framebuffer *fb,
 				       struct drm_rect *clip, bool swab)
 {
 	size_t linepixels = clip->x2 - clip->x1;
 	size_t dst_len = linepixels * sizeof(u16);
 	unsigned y, lines = clip->y2 - clip->y1;
 	void *dbuf;

 	dbuf = kmalloc(dst_len, GFP_KERNEL);
 	if (!dbuf)
 		return;

 	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
 	dst += clip_offset(clip, dst_pitch, sizeof(u16));
 	for (y = 0; y < lines; y++) {
 		drm_fb_xrgb8888_to_rgb565_line(dbuf, vaddr, linepixels, swab);
 		memcpy_toio(dst, dbuf, dst_len);
 		vaddr += fb->pitches[0];
 		dst += dst_len;
 	}

 	kfree(dbuf);
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565_dstclip);

 static void drm_fb_xrgb8888_to_rgb888_line(u8 *dbuf, u32 *sbuf,
 					   unsigned int pixels)
 {
 	unsigned int x;

 	for (x = 0; x < pixels; x++) {
 		*dbuf++ = (sbuf[x] & 0x000000FF) >>  0;
 		*dbuf++ = (sbuf[x] & 0x0000FF00) >>  8;
 		*dbuf++ = (sbuf[x] & 0x00FF0000) >> 16;
 	}
 }

 /**
  * drm_fb_xrgb8888_to_rgb888_dstclip - Convert XRGB8888 to RGB888 clip buffer
  * @dst: RGB565 destination buffer (iomem)
  * @dst_pitch: destination buffer pitch
  * @vaddr: XRGB8888 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  *
  * Drivers can use this function for RGB888 devices that don't natively
  * support XRGB8888.
  *
  * This function applies clipping on dst, i.e. the destination is a
  * full (iomem) framebuffer but only the clip rect content is copied over.
  */
 void drm_fb_xrgb8888_to_rgb888_dstclip(void __iomem *dst, unsigned int dst_pitch,
 				       void *vaddr, struct drm_framebuffer *fb,
 				       struct drm_rect *clip)
 {
 	size_t linepixels = clip->x2 - clip->x1;
 	size_t dst_len = linepixels * 3;
 	unsigned y, lines = clip->y2 - clip->y1;
 	void *dbuf;

 	dbuf = kmalloc(dst_len, GFP_KERNEL);
 	if (!dbuf)
 		return;

 	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
 	dst += clip_offset(clip, dst_pitch, sizeof(u16));
 	for (y = 0; y < lines; y++) {
 		drm_fb_xrgb8888_to_rgb888_line(dbuf, vaddr, linepixels);
 		memcpy_toio(dst, dbuf, dst_len);
 		vaddr += fb->pitches[0];
 		dst += dst_len;
 	}

 	kfree(dbuf);
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb888_dstclip);

 /**
  * drm_fb_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
  * @dst: 8-bit grayscale destination buffer
  * @vaddr: XRGB8888 source buffer
  * @fb: DRM framebuffer
  * @clip: Clip rectangle area to copy
  *
  * Drm doesn't have native monochrome or grayscale support.
  * Such drivers can announce the commonly supported XR24 format to userspace
  * and use this function to convert to the native format.
  *
  * Monochrome drivers will use the most significant bit,
  * where 1 means foreground color and 0 background color.
  *
  * ITU BT.601 is used for the RGB -> luma (brightness) conversion.
  */
 void drm_fb_xrgb8888_to_gray8(u8 *dst, void *vaddr, struct drm_framebuffer *fb,
 			       struct drm_rect *clip)
 {
 	unsigned int len = (clip->x2 - clip->x1) * sizeof(u32);
 	unsigned int x, y;
 	void *buf;
 	u32 *src;

 	if (WARN_ON(fb->format->format != DRM_FORMAT_XRGB8888))
 		return;
 	/*
 	 * The cma memory is write-combined so reads are uncached.
 	 * Speed up by fetching one line at a time.
 	 */
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return;

 	for (y = clip->y1; y < clip->y2; y++) {
 		src = vaddr + (y * fb->pitches[0]);
 		src += clip->x1;
 		memcpy(buf, src, len);
 		src = buf;
 		for (x = clip->x1; x < clip->x2; x++) {
 			u8 r = (*src & 0x00ff0000) >> 16;
 			u8 g = (*src & 0x0000ff00) >> 8;
 			u8 b =  *src & 0x000000ff;

 			/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
 			*dst++ = (3 * r + 6 * g + b) / 10;
 			src++;
 		}
 	}

 	kfree(buf);
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);
	// SPDX-License-Identifier: GPL-2.0 or MIT
	/*
	* Copyright (C) 2016 Noralf Trønnes
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*/

	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/io.h>

	#include <drm/drm_format_helper.h>
	#include <drm/drm_framebuffer.h>
	#include <drm/drm_fourcc.h>
	#include <drm/drm_rect.h>

	static unsigned int clip_offset(struct drm_rect *clip,
	unsigned int pitch, unsigned int cpp)
	{
	return clip->y1 * pitch + clip->x1 * cpp;
	}

	/**
	* drm_fb_memcpy - Copy clip buffer
	* @dst: Destination buffer
	* @vaddr: Source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*
	* This function does not apply clipping on dst, i.e. the destination
	* is a small buffer containing the clip rect only.
	*/
	void drm_fb_memcpy(void dst, void vaddr, struct drm_framebuffer *fb,
	struct drm_rect *clip)
	{
	unsigned int cpp = fb->format->cpp[0];
	size_t len = (clip->x2 - clip->x1) * cpp;
	unsigned int y, lines = clip->y2 - clip->y1;

	vaddr += clip_offset(clip, fb->pitches[0], cpp);
	for (y = 0; y < lines; y++) {
	memcpy(dst, vaddr, len);
	vaddr += fb->pitches[0];
	dst += len;
	}
	}
	EXPORT_SYMBOL(drm_fb_memcpy);

	/**
	* drm_fb_memcpy_dstclip - Copy clip buffer
	* @dst: Destination buffer (iomem)
	* @vaddr: Source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*
	* This function applies clipping on dst, i.e. the destination is a
	* full (iomem) framebuffer but only the clip rect content is copied over.
	*/
	void drm_fb_memcpy_dstclip(void __iomem dst, void vaddr,
	struct drm_framebuffer *fb,
	struct drm_rect *clip)
	{
	unsigned int cpp = fb->format->cpp[0];
	unsigned int offset = clip_offset(clip, fb->pitches[0], cpp);
	size_t len = (clip->x2 - clip->x1) * cpp;
	unsigned int y, lines = clip->y2 - clip->y1;

	vaddr += offset;
	dst += offset;
	for (y = 0; y < lines; y++) {
	memcpy_toio(dst, vaddr, len);
	vaddr += fb->pitches[0];
	dst += fb->pitches[0];
	}
	}
	EXPORT_SYMBOL(drm_fb_memcpy_dstclip);

	/**
	* drm_fb_swab - Swap bytes into clip buffer
	* @dst: Destination buffer
	* @src: Source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	* @cached: Source buffer is mapped cached (eg. not write-combined)
	*
	* If @cached is false a temporary buffer is used to cache one pixel line at a
	* time to speed up slow uncached reads.
	*
	* This function does not apply clipping on dst, i.e. the destination
	* is a small buffer containing the clip rect only.
	*/
	void drm_fb_swab(void dst, void src, struct drm_framebuffer *fb,
	struct drm_rect *clip, bool cached)
	{
	u8 cpp = fb->format->cpp[0];
	size_t len = drm_rect_width(clip) * cpp;
	u16 src16, dst16 = dst;
	u32 src32, dst32 = dst;
	unsigned int x, y;
	void *buf = NULL;

	if (WARN_ON_ONCE(cpp != 2 && cpp != 4))
	return;

	if (!cached)
	buf = kmalloc(len, GFP_KERNEL);

	src += clip_offset(clip, fb->pitches[0], cpp);

	for (y = clip->y1; y < clip->y2; y++) {
	if (buf) {
	memcpy(buf, src, len);
	src16 = buf;
	src32 = buf;
	} else {
	src16 = src;
	src32 = src;
	}

	for (x = clip->x1; x < clip->x2; x++) {
	if (cpp == 4)
	dst32++ = swab32(src32++);
	else
	dst16++ = swab16(src16++);
	}

	src += fb->pitches[0];
	}

	kfree(buf);
	}
	EXPORT_SYMBOL(drm_fb_swab);

	static void drm_fb_xrgb8888_to_rgb565_line(u16 dbuf, u32 sbuf,
	unsigned int pixels,
	bool swab)
	{
	unsigned int x;
	u16 val16;

	for (x = 0; x < pixels; x++) {
	val16 = ((sbuf[x] & 0x00F80000) >> 8) \|
	((sbuf[x] & 0x0000FC00) >> 5) \|
	((sbuf[x] & 0x000000F8) >> 3);
	if (swab)
	dbuf[x] = swab16(val16);
	else
	dbuf[x] = val16;
	}
	}

	/**
	* drm_fb_xrgb8888_to_rgb565 - Convert XRGB8888 to RGB565 clip buffer
	* @dst: RGB565 destination buffer
	* @vaddr: XRGB8888 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	* @swab: Swap bytes
	*
	* Drivers can use this function for RGB565 devices that don't natively
	* support XRGB8888.
	*
	* This function does not apply clipping on dst, i.e. the destination
	* is a small buffer containing the clip rect only.
	*/
	void drm_fb_xrgb8888_to_rgb565(void dst, void vaddr,
	struct drm_framebuffer *fb,
	struct drm_rect *clip, bool swab)
	{
	size_t linepixels = clip->x2 - clip->x1;
	size_t src_len = linepixels * sizeof(u32);
	size_t dst_len = linepixels * sizeof(u16);
	unsigned y, lines = clip->y2 - clip->y1;
	void *sbuf;

	/*
	* The cma memory is write-combined so reads are uncached.
	* Speed up by fetching one line at a time.
	*/
	sbuf = kmalloc(src_len, GFP_KERNEL);
	if (!sbuf)
	return;

	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
	for (y = 0; y < lines; y++) {
	memcpy(sbuf, vaddr, src_len);
	drm_fb_xrgb8888_to_rgb565_line(dst, sbuf, linepixels, swab);
	vaddr += fb->pitches[0];
	dst += dst_len;
	}

	kfree(sbuf);
	}
	EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565);

	/**
	* drm_fb_xrgb8888_to_rgb565_dstclip - Convert XRGB8888 to RGB565 clip buffer
	* @dst: RGB565 destination buffer (iomem)
	* @dst_pitch: destination buffer pitch
	* @vaddr: XRGB8888 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	* @swab: Swap bytes
	*
	* Drivers can use this function for RGB565 devices that don't natively
	* support XRGB8888.
	*
	* This function applies clipping on dst, i.e. the destination is a
	* full (iomem) framebuffer but only the clip rect content is copied over.
	*/
	void drm_fb_xrgb8888_to_rgb565_dstclip(void __iomem *dst, unsigned int dst_pitch,
	void vaddr, struct drm_framebuffer fb,
	struct drm_rect *clip, bool swab)
	{
	size_t linepixels = clip->x2 - clip->x1;
	size_t dst_len = linepixels * sizeof(u16);
	unsigned y, lines = clip->y2 - clip->y1;
	void *dbuf;

	dbuf = kmalloc(dst_len, GFP_KERNEL);
	if (!dbuf)
	return;

	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
	dst += clip_offset(clip, dst_pitch, sizeof(u16));
	for (y = 0; y < lines; y++) {
	drm_fb_xrgb8888_to_rgb565_line(dbuf, vaddr, linepixels, swab);
	memcpy_toio(dst, dbuf, dst_len);
	vaddr += fb->pitches[0];
	dst += dst_len;
	}

	kfree(dbuf);
	}
	EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb565_dstclip);

	static void drm_fb_xrgb8888_to_rgb888_line(u8 dbuf, u32 sbuf,
	unsigned int pixels)
	{
	unsigned int x;

	for (x = 0; x < pixels; x++) {
	*dbuf++ = (sbuf[x] & 0x000000FF) >> 0;
	*dbuf++ = (sbuf[x] & 0x0000FF00) >> 8;
	*dbuf++ = (sbuf[x] & 0x00FF0000) >> 16;
	}
	}

	/**
	* drm_fb_xrgb8888_to_rgb888_dstclip - Convert XRGB8888 to RGB888 clip buffer
	* @dst: RGB565 destination buffer (iomem)
	* @dst_pitch: destination buffer pitch
	* @vaddr: XRGB8888 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*
	* Drivers can use this function for RGB888 devices that don't natively
	* support XRGB8888.
	*
	* This function applies clipping on dst, i.e. the destination is a
	* full (iomem) framebuffer but only the clip rect content is copied over.
	*/
	void drm_fb_xrgb8888_to_rgb888_dstclip(void __iomem *dst, unsigned int dst_pitch,
	void vaddr, struct drm_framebuffer fb,
	struct drm_rect *clip)
	{
	size_t linepixels = clip->x2 - clip->x1;
	size_t dst_len = linepixels * 3;
	unsigned y, lines = clip->y2 - clip->y1;
	void *dbuf;

	dbuf = kmalloc(dst_len, GFP_KERNEL);
	if (!dbuf)
	return;

	vaddr += clip_offset(clip, fb->pitches[0], sizeof(u32));
	dst += clip_offset(clip, dst_pitch, sizeof(u16));
	for (y = 0; y < lines; y++) {
	drm_fb_xrgb8888_to_rgb888_line(dbuf, vaddr, linepixels);
	memcpy_toio(dst, dbuf, dst_len);
	vaddr += fb->pitches[0];
	dst += dst_len;
	}

	kfree(dbuf);
	}
	EXPORT_SYMBOL(drm_fb_xrgb8888_to_rgb888_dstclip);

	/**
	* drm_fb_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
	* @dst: 8-bit grayscale destination buffer
	* @vaddr: XRGB8888 source buffer
	* @fb: DRM framebuffer
	* @clip: Clip rectangle area to copy
	*
	* Drm doesn't have native monochrome or grayscale support.
	* Such drivers can announce the commonly supported XR24 format to userspace
	* and use this function to convert to the native format.
	*
	* Monochrome drivers will use the most significant bit,
	* where 1 means foreground color and 0 background color.
	*
	* ITU BT.601 is used for the RGB -> luma (brightness) conversion.
	*/
	void drm_fb_xrgb8888_to_gray8(u8 dst, void vaddr, struct drm_framebuffer *fb,
	struct drm_rect *clip)
	{
	unsigned int len = (clip->x2 - clip->x1) * sizeof(u32);
	unsigned int x, y;
	void *buf;
	u32 *src;

	if (WARN_ON(fb->format->format != DRM_FORMAT_XRGB8888))
	return;
	/*
	* The cma memory is write-combined so reads are uncached.
	* Speed up by fetching one line at a time.
	*/
	buf = kmalloc(len, GFP_KERNEL);
	if (!buf)
	return;

	for (y = clip->y1; y < clip->y2; y++) {
	src = vaddr + (y * fb->pitches[0]);
	src += clip->x1;
	memcpy(buf, src, len);
	src = buf;
	for (x = clip->x1; x < clip->x2; x++) {
	u8 r = (*src & 0x00ff0000) >> 16;
	u8 g = (*src & 0x0000ff00) >> 8;
	u8 b = *src & 0x000000ff;

	/* ITU BT.601: Y = 0.299 R + 0.587 G + 0.114 B */
	dst++ = (3 r + 6 * g + b) / 10;
	src++;
	}
	}

	kfree(buf);
	}
	EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);