drm/format-helper: Rework XRGB8888-to-GRAY8 conversion

Update XRGB8888-to-GRAY8 conversion to support struct iosys_map
and convert all users. Although these are single-plane color formats,
the new interface supports multi-plane formats for consistency with
drm_fb_blit().

v2:
	* update documentation (Sam)
	* add TODO on vaddr location (Sam)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Noralf Trønnes <noralf@tronnes.org>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20220808125406.20752-12-tzimmermann@suse.de

drivers/gpu/drm/drm_format_helper.c

@@ -613,25 +613,47 @@ static void drm_fb_xrgb8888_to_gray8_line(void *dbuf, const void *sbuf, unsigned
 
 /**
  * drm_fb_xrgb8888_to_gray8 - Convert XRGB8888 to grayscale
- * @dst: 8-bit grayscale destination buffer
- * @dst_pitch: Number of bytes between two consecutive scanlines within dst
- * @vaddr: XRGB8888 source buffer
+ * @dst: Array of 8-bit grayscale destination buffers
+ * @dst_pitch: Array of numbers of bytes between the start of two consecutive scanlines
+ *             within @dst; can be NULL if scanlines are stored next to each other.
+ * @vmap: Array of XRGB8888 source buffers
  * @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.
+ * This function copies parts of a framebuffer to display memory and converts the
+ * color format during the process. Destination and framebuffer formats must match. The
+ * parameters @dst, @dst_pitch and @vmap refer to arrays. Each array must have at
+ * least as many entries as there are planes in @fb's format. Each entry stores the
+ * value for the format's respective color plane at the same index.
  *
- * Monochrome drivers will use the most significant bit,
- * where 1 means foreground color and 0 background color.
+ * This function does not apply clipping on @dst (i.e. the destination is at the
+ * top-left corner).
  *
- * ITU BT.601 is used for the RGB -> luma (brightness) conversion.
+ * DRM doesn't have native monochrome or grayscale support. Drivers can use this
+ * function for grayscale devices that don't support XRGB8888 natively.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 being used for the RGB -> luma (brightness) conversion.
  */
-void drm_fb_xrgb8888_to_gray8(void *dst, unsigned int dst_pitch, const void *vaddr,
-			      const struct drm_framebuffer *fb, const struct drm_rect *clip)
+void drm_fb_xrgb8888_to_gray8(struct iosys_map *dst, const unsigned int *dst_pitch,
+			      const struct iosys_map *vmap, const struct drm_framebuffer *fb,
+			      const struct drm_rect *clip)
 {
-	drm_fb_xfrm(dst, dst_pitch, 1, vaddr, fb, clip, false, drm_fb_xrgb8888_to_gray8_line);
+	static const unsigned int default_dst_pitch[DRM_FORMAT_MAX_PLANES] = {
+		0, 0, 0, 0
+	};
+
+	if (!dst_pitch)
+		dst_pitch = default_dst_pitch;
+
+	/* TODO: handle vmap in I/O memory here */
+	if (dst[0].is_iomem)
+		drm_fb_xfrm_toio(dst[0].vaddr_iomem, dst_pitch[0], 1, vmap[0].vaddr, fb,
+				 clip, false, drm_fb_xrgb8888_to_gray8_line);
+	else
+		drm_fb_xfrm(dst[0].vaddr, dst_pitch[0], 1, vmap[0].vaddr, fb,
+			    clip, false, drm_fb_xrgb8888_to_gray8_line);
 }
 EXPORT_SYMBOL(drm_fb_xrgb8888_to_gray8);
 

drivers/gpu/drm/gud/gud_pipe.c

@@ -59,6 +59,7 @@ static size_t gud_xrgb8888_to_r124(u8 *dst, const struct drm_format_info *format
 	unsigned int bits_per_pixel = 8 / block_width;
 	unsigned int x, y, width, height;
 	u8 pix, *pix8, *block = dst; /* Assign to silence compiler warning */
+	struct iosys_map dst_map, vmap;
 	size_t len;
 	void *buf;
 
@@ -74,7 +75,9 @@ static size_t gud_xrgb8888_to_r124(u8 *dst, const struct drm_format_info *format
 	if (!buf)
 		return 0;
 
-	drm_fb_xrgb8888_to_gray8(buf, 0, src, fb, rect);
+	iosys_map_set_vaddr(&dst_map, buf);
+	iosys_map_set_vaddr(&vmap, src);
+	drm_fb_xrgb8888_to_gray8(&dst_map, NULL, &vmap, fb, rect);
 	pix8 = buf;
 
 	for (y = 0; y < height; y++) {
@@ -194,7 +197,7 @@ retry:
 				goto end_cpu_access;
 			}
 		} else if (format->format == DRM_FORMAT_R8) {
-			drm_fb_xrgb8888_to_gray8(buf, 0, vaddr, fb, rect);
+			drm_fb_xrgb8888_to_gray8(&dst, NULL, map_data, fb, rect);
 		} else if (format->format == DRM_FORMAT_RGB332) {
 			drm_fb_xrgb8888_to_rgb332(&dst, NULL, map_data, fb, rect);
 		} else if (format->format == DRM_FORMAT_RGB565) {

drivers/gpu/drm/tiny/st7586.c

@@ -69,12 +69,15 @@ static void st7586_xrgb8888_to_gray332(u8 *dst, void *vaddr,
 	size_t len = (clip->x2 - clip->x1) * (clip->y2 - clip->y1);
 	unsigned int x, y;
 	u8 *src, *buf, val;
+	struct iosys_map dst_map, vmap;
 
 	buf = kmalloc(len, GFP_KERNEL);
 	if (!buf)
 		return;
 
-	drm_fb_xrgb8888_to_gray8(buf, 0, vaddr, fb, clip);
+	iosys_map_set_vaddr(&dst_map, buf);
+	iosys_map_set_vaddr(&vmap, vaddr);
+	drm_fb_xrgb8888_to_gray8(&dst_map, NULL, &vmap, fb, clip);
 	src = buf;
 
 	for (y = clip->y1; y < clip->y2; y++) {

include/drm/drm_format_helper.h

@@ -32,8 +32,9 @@ void drm_fb_xrgb8888_to_rgb888(struct iosys_map *dst, const unsigned int *dst_pi
 void drm_fb_xrgb8888_to_xrgb2101010(struct iosys_map *dst, const unsigned int *dst_pitch,
 				    const struct iosys_map *vmap, const struct drm_framebuffer *fb,
 				    const struct drm_rect *clip);
-void drm_fb_xrgb8888_to_gray8(void *dst, unsigned int dst_pitch, const void *vaddr,
-			      const struct drm_framebuffer *fb, const struct drm_rect *clip);
+void drm_fb_xrgb8888_to_gray8(struct iosys_map *dst, const unsigned int *dst_pitch,
+			      const struct iosys_map *vmap, const struct drm_framebuffer *fb,
+			      const struct drm_rect *clip);
 
 int drm_fb_blit(struct iosys_map *dst, const unsigned int *dst_pitch, uint32_t dst_format,
 		const struct iosys_map *vmap, const struct drm_framebuffer *fb,