[Mesa-dev] [PATCH] egl, wayland: RGB565 format support on Back-buffer

[Dongwon Kim]

From: Vivek Kasireddy <vivek.kasireddy at intel.com>

In current code, color format is always hardcoded to
__DRI_IMAGE_FORMAT_ARGB8888 when buffer or DRI image is
allocated in function calls, get_back_bo and dri2_get_buffers,
regardless of current target's color format. This problem
may leads to incorrect render pitch calculation, which
eventually ends up with wrong offset of pixels in
the frame buffer when the image is in different color format
from dri surf's, especially with different bpp. (e.g. RGB565-16bpp)

Attached code patch simply adds RGB565 and XRGB8888 cases to two
functions noted above to resolve the issue.

v2: added a case of XRGB8888, format and bpp selection is done
    via switch-case (not "if-else" anymore)

Signed-off-by: Vivek Kasireddy <vivek.kasireddy at intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim at intel.com>
---
 src/egl/drivers/dri2/platform_wayland.c |   41 ++++++++++++++++++++++++++++---
 1 file changed, 38 insertions(+), 3 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 3c34e07..07f68a2 100644
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -292,6 +292,26 @@ get_back_bo(struct dri2_egl_surface *dri2_surf)
    struct dri2_egl_display *dri2_dpy =
       dri2_egl_display(dri2_surf->base.Resource.Display);
    int i;
+   unsigned int dri_image_format;
+
+   /* currently supports three WL DRM formats,
+    * WL_DRM_FORMAT_ARGB8888, WL_DRM_FORMAT_XRGB8888,
+    * and WL_DRM_FORMAT_RGB565
+    */
+   switch (dri2_surf->format) {
+   case WL_DRM_FORMAT_ARGB8888:
+      dri_image_format = __DRI_IMAGE_FORMAT_ARGB8888;
+      break;
+   case WL_DRM_FORMAT_XRGB8888:
+      dri_image_format = __DRI_IMAGE_FORMAT_XRGB8888;
+      break;
+   case WL_DRM_FORMAT_RGB565:
+      dri_image_format = __DRI_IMAGE_FORMAT_RGB565;
+      break;
+   default:
+      /* format is not supported */
+      return -1;
+   }
 
    /* We always want to throttle to some event (either a frame callback or
     * a sync request) after the commit so that we can be sure the
@@ -322,7 +342,7 @@ get_back_bo(struct dri2_egl_surface *dri2_surf)
          dri2_dpy->image->createImage(dri2_dpy->dri_screen,
                                       dri2_surf->base.Width,
                                       dri2_surf->base.Height,
-                                      __DRI_IMAGE_FORMAT_ARGB8888,
+                                      dri_image_format,
                                       __DRI_IMAGE_USE_SHARE,
                                       NULL);
       dri2_surf->back->age = 0;
@@ -462,11 +482,26 @@ dri2_wl_get_buffers(__DRIdrawable * driDrawable,
                     unsigned int *attachments, int count,
                     int *out_count, void *loaderPrivate)
 {
+   struct dri2_egl_surface *dri2_surf = loaderPrivate;
    unsigned int *attachments_with_format;
    __DRIbuffer *buffer;
-   const unsigned int format = 32;
+   unsigned int bpp;
+
    int i;
 
+   switch (dri2_surf->format) {
+   case WL_DRM_FORMAT_ARGB8888:
+   case WL_DRM_FORMAT_XRGB8888:
+      bpp = 32;
+      break;
+   case WL_DRM_FORMAT_RGB565:
+      bpp = 16;
+      break;
+   default:
+      /* format is not supported */
+      return NULL;
+   }
+
    attachments_with_format = calloc(count, 2 * sizeof(unsigned int));
    if (!attachments_with_format) {
       *out_count = 0;
@@ -475,7 +510,7 @@ dri2_wl_get_buffers(__DRIdrawable * driDrawable,
 
    for (i = 0; i < count; ++i) {
       attachments_with_format[2*i] = attachments[i];
-      attachments_with_format[2*i + 1] = format;
+      attachments_with_format[2*i + 1] = bpp;
    }
 
    buffer =
-- 
1.7.9.5