[PATCH v1 5/7] ui/spice: Override the surface's glformat when gl=on is enabled

[Vivek Kasireddy <vivek.kasireddy@intel.com>]

When testing with gl=on on an Intel Host, it was noticed that the
R and B channels were interchanged while the Guest FB image was
displayed. This was only seen if the display layer (virtio-gpu)
did not directly share the dmabuf fd with Spice (i.e, blob=false).

One of the main differences in the case where blob=true vs blob=false
is that we create the dmabuf fd from a texture in the latter case
whereas we directly pass the fd from the display layer to Spice in
the former case. Although, the surface's format (PIXMAN_BE_b8g8r8x8)
is the same in both cases, the creation of the texture (which involves
copying data from Pixman image into a GPU buffer) appears to somehow
result in having the R and B channels interchanged. One way to ensure
correct behavior is we have glformat=GL_RGBA while creating the texture.

It looks like having glformat=GL_RGBA and gltype = GL_UNSIGNED_BYTE
should work regardless of the Host's endianness but let us limit
this change only to this specific use-case for now.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Frediano Ziglio <freddy77@gmail.com>
Cc: Dongwon Kim <dongwon.kim@intel.com>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
---
 ui/spice-display.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/ui/spice-display.c b/ui/spice-display.c
index 90c04623ec..08b4aec921 100644
--- a/ui/spice-display.c
+++ b/ui/spice-display.c
@@ -900,6 +900,9 @@ static void spice_gl_switch(DisplayChangeListener *dcl,
     }
     ssd->ds = new_surface;
     if (ssd->ds) {
+        if (remote_client && surface_format(ssd->ds) != PIXMAN_r5g6b5) {
+            ssd->ds->target_glformat = GL_RGBA;
+        }
         surface_gl_create_texture(ssd->gls, ssd->ds);
         fd = egl_get_fd_for_texture(ssd->ds->texture,
                                     &stride, &fourcc,
-- 
2.39.2