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

[Dongwon Kim]

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. 16bpp)

Attached code patch simply adds RGB565 case to two functions noted above to resolve
the issue.

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 |   10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/egl/drivers/dri2/platform_wayland.c b/src/egl/drivers/dri2/platform_wayland.c
index 3c34e07..78761e2 100644
--- a/src/egl/drivers/dri2/platform_wayland.c
+++ b/src/egl/drivers/dri2/platform_wayland.c
@@ -293,6 +293,11 @@ get_back_bo(struct dri2_egl_surface *dri2_surf)
       dri2_egl_display(dri2_surf->base.Resource.Display);
    int i;
 
+   /* currently supports two DRI image formats, __DRI_IMAGE_FORMAT_RGB565 or __DRI_IMAGE_FORMAT_ARGB8888,
+    * one of which is selected depending on dri surface format */
+   const unsigned int dri_image_format =
+        (dri2_surf->format == WL_DRM_FORMAT_RGB565) ? __DRI_IMAGE_FORMAT_RGB565 : __DRI_IMAGE_FORMAT_ARGB8888;
+
    /* 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
     * compositor has had a chance to handle it and send us a release event
@@ -322,7 +327,7 @@ 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;
@@ -462,9 +467,10 @@ 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;
+   const unsigned int format = (dri2_surf->format == WL_DRM_FORMAT_RGB565) ? 16 : 32;
    int i;
 
    attachments_with_format = calloc(count, 2 * sizeof(unsigned int));
-- 
1.7.9.5