drm/vkms: Add support for RGB565 formats

The format RGB565 was already supported. Add the support for:
- BGR565

Reviewed-by: Maíra Canal <mcanal@igalia.com>
Acked-by: Daniel Stone <daniels@collabora.com>
Link: https://lore.kernel.org/r/20250703-b4-new-color-formats-v7-4-15fd8fd2e15c@bootlin.com
Signed-off-by: Louis Chauvet <louis.chauvet@bootlin.com>

Author: Fomys

drivers/gpu/drm/vkms/vkms_formats.c

@@ -259,6 +259,16 @@ static struct pixel_argb_u16 argb_u16_from_grayu16(u16 gray)
 	return argb_u16_from_u16161616(0xFFFF, gray, gray, gray);
 }
 
+static struct pixel_argb_u16 argb_u16_from_BGR565(const __le16 *pixel)
+{
+	struct pixel_argb_u16 out_pixel;
+
+	out_pixel = argb_u16_from_RGB565(pixel);
+	swap(out_pixel.r, out_pixel.b);
+
+	return out_pixel;
+}
+
 VISIBLE_IF_KUNIT struct pixel_argb_u16 argb_u16_from_yuv888(u8 y, u8 channel_1, u8 channel_2,
 							    const struct conversion_matrix *matrix)
 {
@@ -451,6 +461,7 @@ READ_LINE_le16161616(XRGB16161616_read_line, px, cpu_to_le16(0xFFFF), px[2], px[
 READ_LINE_le16161616(XBGR16161616_read_line, px, cpu_to_le16(0xFFFF), px[0], px[1], px[2])
 
 READ_LINE(RGB565_read_line, px, __le16, argb_u16_from_RGB565, px)
+READ_LINE(BGR565_read_line, px, __le16, argb_u16_from_BGR565, px)
 
 READ_LINE(R8_read_line, px, u8, argb_u16_from_gray8, *px)
 
@@ -675,6 +686,8 @@ pixel_read_line_t get_pixel_read_line_function(u32 format)
 		return &XBGR16161616_read_line;
 	case DRM_FORMAT_RGB565:
 		return &RGB565_read_line;
+	case DRM_FORMAT_BGR565:
+		return &BGR565_read_line;
 	case DRM_FORMAT_NV12:
 	case DRM_FORMAT_NV16:
 	case DRM_FORMAT_NV24:

drivers/gpu/drm/vkms/vkms_plane.c

@@ -24,6 +24,7 @@ static const u32 vkms_formats[] = {
 	DRM_FORMAT_ARGB16161616,
 	DRM_FORMAT_ABGR16161616,
 	DRM_FORMAT_RGB565,
+	DRM_FORMAT_BGR565,
 	DRM_FORMAT_NV12,
 	DRM_FORMAT_NV16,
 	DRM_FORMAT_NV24,