[PATCH] drm/vkms: Add support for ABGR8888 pixel format

[Paz Zcharya <pazz@chromium.org>]

Add support for pixel format ABGR8888, which is the default format
on Android devices. This will allow us to use VKMS as the default
display driver in Android Emulator (Cuttlefish) and increase VKMS
adoption.

Changes in v2:
- Rebased on top of tip of tree because it has been 3 months.
- No functional changes.

Signed-off-by: Paz Zcharya <pazz@google.com>
---

 drivers/gpu/drm/vkms/vkms_formats.c   | 32 +++++++++++++++++++++++++++
 drivers/gpu/drm/vkms/vkms_plane.c     |  1 +
 drivers/gpu/drm/vkms/vkms_writeback.c |  1 +
 3 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/vkms/vkms_formats.c b/drivers/gpu/drm/vkms/vkms_formats.c
index 39b1d7c97d45..30a64ecca87c 100644
--- a/drivers/gpu/drm/vkms/vkms_formats.c
+++ b/drivers/gpu/drm/vkms/vkms_formats.c
@@ -253,6 +253,26 @@ static void XRGB8888_read_line(const struct vkms_plane_state *plane, int x_start
 	}
 }
 
+static void ABGR8888_read_line(const struct vkms_plane_state *plane, int x_start, int y_start,
+			       enum pixel_read_direction direction, int count,
+			       struct pixel_argb_u16 out_pixel[])
+{
+	struct pixel_argb_u16 *end = out_pixel + count;
+	u8 *src_pixels;
+
+	packed_pixels_addr_1x1(plane->frame_info, x_start, y_start, 0, &src_pixels);
+
+	int step = get_block_step_bytes(plane->frame_info->fb, direction, 0);
+
+	while (out_pixel < end) {
+		u8 *px = (u8 *)src_pixels;
+		/* Switch blue and red pixels. */
+		*out_pixel = argb_u16_from_u8888(px[3], px[0], px[1], px[2]);
+		out_pixel += 1;
+		src_pixels += step;
+	}
+}
+
 static void ARGB16161616_read_line(const struct vkms_plane_state *plane, int x_start,
 				   int y_start, enum pixel_read_direction direction, int count,
 				   struct pixel_argb_u16 out_pixel[])
@@ -344,6 +364,14 @@ static void argb_u16_to_XRGB8888(u8 *out_pixel, const struct pixel_argb_u16 *in_
 	out_pixel[0] = DIV_ROUND_CLOSEST(in_pixel->b, 257);
 }
 
+static void argb_u16_to_ABGR8888(u8 *out_pixel, const struct pixel_argb_u16 *in_pixel)
+{
+	out_pixel[3] = DIV_ROUND_CLOSEST(in_pixel->a, 257);
+	out_pixel[2] = DIV_ROUND_CLOSEST(in_pixel->b, 257);
+	out_pixel[1] = DIV_ROUND_CLOSEST(in_pixel->g, 257);
+	out_pixel[0] = DIV_ROUND_CLOSEST(in_pixel->r, 257);
+}
+
 static void argb_u16_to_ARGB16161616(u8 *out_pixel, const struct pixel_argb_u16 *in_pixel)
 {
 	__le16 *pixel = (__le16 *)out_pixel;
@@ -420,6 +448,8 @@ pixel_read_line_t get_pixel_read_line_function(u32 format)
 		return &ARGB8888_read_line;
 	case DRM_FORMAT_XRGB8888:
 		return &XRGB8888_read_line;
+	case DRM_FORMAT_ABGR8888:
+		return &ABGR8888_read_line;
 	case DRM_FORMAT_ARGB16161616:
 		return &ARGB16161616_read_line;
 	case DRM_FORMAT_XRGB16161616:
@@ -453,6 +483,8 @@ pixel_write_t get_pixel_write_function(u32 format)
 		return &argb_u16_to_ARGB8888;
 	case DRM_FORMAT_XRGB8888:
 		return &argb_u16_to_XRGB8888;
+	case DRM_FORMAT_ABGR8888:
+		return &argb_u16_to_ABGR8888;
 	case DRM_FORMAT_ARGB16161616:
 		return &argb_u16_to_ARGB16161616;
 	case DRM_FORMAT_XRGB16161616:
diff --git a/drivers/gpu/drm/vkms/vkms_plane.c b/drivers/gpu/drm/vkms/vkms_plane.c
index e2fce471870f..e34f8c7f83c3 100644
--- a/drivers/gpu/drm/vkms/vkms_plane.c
+++ b/drivers/gpu/drm/vkms/vkms_plane.c
@@ -15,6 +15,7 @@
 static const u32 vkms_formats[] = {
 	DRM_FORMAT_ARGB8888,
 	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_ABGR8888,
 	DRM_FORMAT_XRGB16161616,
 	DRM_FORMAT_ARGB16161616,
 	DRM_FORMAT_RGB565
diff --git a/drivers/gpu/drm/vkms/vkms_writeback.c b/drivers/gpu/drm/vkms/vkms_writeback.c
index e9b5c74d7c58..fe163271d5b5 100644
--- a/drivers/gpu/drm/vkms/vkms_writeback.c
+++ b/drivers/gpu/drm/vkms/vkms_writeback.c
@@ -17,6 +17,7 @@
 static const u32 vkms_wb_formats[] = {
 	DRM_FORMAT_ARGB8888,
 	DRM_FORMAT_XRGB8888,
+	DRM_FORMAT_ABGR8888,
 	DRM_FORMAT_XRGB16161616,
 	DRM_FORMAT_ARGB16161616,
 	DRM_FORMAT_RGB565
-- 
2.48.1.262.g85cc9f2d1e-goog