drm/panic: Add integer scaling to blit()

Add a parameter to the blit function, to upscale the image.
This is necessary to draw a QR code, otherwise, the pixels are
usually too small to be readable by most QR code reader.
It can also be used later for drawing fonts on high DPI display.

Signed-off-by: Jocelyn Falempe <jfalempe@redhat.com>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240822073852.562286-2-jfalempe@redhat.com

drivers/gpu/drm/drm_panic.c

@@ -257,28 +257,28 @@ static bool drm_panic_is_pixel_fg(const u8 *sbuf8, unsigned int spitch, int x, i
 static void drm_panic_blit16(struct iosys_map *dmap, unsigned int dpitch,
 			     const u8 *sbuf8, unsigned int spitch,
 			     unsigned int height, unsigned int width,
-			     u16 fg16)
+			     unsigned int scale, u16 fg16)
 {
 	unsigned int y, x;
 
 	for (y = 0; y < height; y++)
 		for (x = 0; x < width; x++)
-			if (drm_panic_is_pixel_fg(sbuf8, spitch, x, y))
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
 				iosys_map_wr(dmap, y * dpitch + x * sizeof(u16), u16, fg16);
 }
 
 static void drm_panic_blit24(struct iosys_map *dmap, unsigned int dpitch,
 			     const u8 *sbuf8, unsigned int spitch,
 			     unsigned int height, unsigned int width,
-			     u32 fg32)
+			     unsigned int scale, u32 fg32)
 {
 	unsigned int y, x;
 
 	for (y = 0; y < height; y++) {
 		for (x = 0; x < width; x++) {
 			u32 off = y * dpitch + x * 3;
 
-			if (drm_panic_is_pixel_fg(sbuf8, spitch, x, y)) {
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale)) {
 				/* write blue-green-red to output in little endianness */
 				iosys_map_wr(dmap, off, u8, (fg32 & 0x000000FF) >> 0);
 				iosys_map_wr(dmap, off + 1, u8, (fg32 & 0x0000FF00) >> 8);
@@ -291,24 +291,25 @@ static void drm_panic_blit24(struct iosys_map *dmap, unsigned int dpitch,
 static void drm_panic_blit32(struct iosys_map *dmap, unsigned int dpitch,
 			     const u8 *sbuf8, unsigned int spitch,
 			     unsigned int height, unsigned int width,
-			     u32 fg32)
+			     unsigned int scale, u32 fg32)
 {
 	unsigned int y, x;
 
 	for (y = 0; y < height; y++)
 		for (x = 0; x < width; x++)
-			if (drm_panic_is_pixel_fg(sbuf8, spitch, x, y))
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
 				iosys_map_wr(dmap, y * dpitch + x * sizeof(u32), u32, fg32);
 }
 
 static void drm_panic_blit_pixel(struct drm_scanout_buffer *sb, struct drm_rect *clip,
-				 const u8 *sbuf8, unsigned int spitch, u32 fg_color)
+				 const u8 *sbuf8, unsigned int spitch, unsigned int scale,
+				 u32 fg_color)
 {
 	unsigned int y, x;
 
 	for (y = 0; y < drm_rect_height(clip); y++)
 		for (x = 0; x < drm_rect_width(clip); x++)
-			if (drm_panic_is_pixel_fg(sbuf8, spitch, x, y))
+			if (drm_panic_is_pixel_fg(sbuf8, spitch, x / scale, y / scale))
 				sb->set_pixel(sb, clip->x1 + x, clip->y1 + y, fg_color);
 }
 
@@ -318,34 +319,38 @@ static void drm_panic_blit_pixel(struct drm_scanout_buffer *sb, struct drm_rect
  * @clip: destination rectangle
  * @sbuf8: source buffer, in monochrome format, 8 pixels per byte.
  * @spitch: source pitch in bytes
+ * @scale: integer scale, source buffer is scale time smaller than destination
+ *         rectangle
  * @fg_color: foreground color, in destination format
  *
  * This can be used to draw a font character, which is a monochrome image, to a
  * framebuffer in other supported format.
  */
 static void drm_panic_blit(struct drm_scanout_buffer *sb, struct drm_rect *clip,
-			   const u8 *sbuf8, unsigned int spitch, u32 fg_color)
+			   const u8 *sbuf8, unsigned int spitch,
+			   unsigned int scale, u32 fg_color)
+
 {
 	struct iosys_map map;
 
 	if (sb->set_pixel)
-		return drm_panic_blit_pixel(sb, clip, sbuf8, spitch, fg_color);
+		return drm_panic_blit_pixel(sb, clip, sbuf8, spitch, scale, fg_color);
 
 	map = sb->map[0];
 	iosys_map_incr(&map, clip->y1 * sb->pitch[0] + clip->x1 * sb->format->cpp[0]);
 
 	switch (sb->format->cpp[0]) {
 	case 2:
 		drm_panic_blit16(&map, sb->pitch[0], sbuf8, spitch,
-				 drm_rect_height(clip), drm_rect_width(clip), fg_color);
+				 drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 	break;
 	case 3:
 		drm_panic_blit24(&map, sb->pitch[0], sbuf8, spitch,
-				 drm_rect_height(clip), drm_rect_width(clip), fg_color);
+				 drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 	break;
 	case 4:
 		drm_panic_blit32(&map, sb->pitch[0], sbuf8, spitch,
-				 drm_rect_height(clip), drm_rect_width(clip), fg_color);
+				 drm_rect_height(clip), drm_rect_width(clip), scale, fg_color);
 	break;
 	default:
 		WARN_ONCE(1, "Can't blit with pixel width %d\n", sb->format->cpp[0]);
@@ -485,7 +490,7 @@ static void draw_txt_rectangle(struct drm_scanout_buffer *sb,
 		for (j = 0; j < line_len; j++) {
 			src = get_char_bitmap(font, msg[i].txt[j], font_pitch);
 			rec.x2 = rec.x1 + font->width;
-			drm_panic_blit(sb, &rec, src, font_pitch, color);
+			drm_panic_blit(sb, &rec, src, font_pitch, 1, color);
 			rec.x1 += font->width;
 		}
 	}