frontends/va: honor DRI_PRIME for VA_DISPLAY_WAYLAND

This matches the X11 behavior. Other display types are unaffected.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/8069
Reviewed-by: Leo Liu <leo.liu@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31012>

src/gallium/auxiliary/vl/vl_winsys.h

@@ -106,7 +106,7 @@ struct vl_screen *vl_win32_screen_create_from_d3d12_device(IUnknown* d3d12_devic
 #else
 /* Always enable the DRM vl winsys */
 struct vl_screen *
-vl_drm_screen_create(int fd);
+vl_drm_screen_create(int fd, bool honor_dri_prime);
 
 #ifdef USE_XSHM
 struct vl_screen *

src/gallium/auxiliary/vl/vl_winsys_drm.c

@@ -34,13 +34,25 @@
 #include "util/u_memory.h"
 #include "vl/vl_winsys.h"
 
+#include "loader.h"
+
 static void
 vl_drm_screen_destroy(struct vl_screen *vscreen);
 
 struct vl_screen *
-vl_drm_screen_create(int fd)
+vl_drm_screen_create(int fd, bool honor_dri_prime)
 {
    struct vl_screen *vscreen;
+   int libva_owned_fd = -1;
+
+   if (honor_dri_prime) {
+      /* Pass a non-NULL value as the 2nd param in order to not
+       * close the original fd - it's owned by libva.
+       * If fd is overriden, we'll close after the call to
+       * pipe_loader_drm_probe_fd because pipe_loader dups the fd.
+       */
+      loader_get_user_preferred_fd(&fd, &libva_owned_fd);
+   }
 
    vscreen = CALLOC_STRUCT(vl_screen);
    if (!vscreen)
@@ -49,6 +61,9 @@ vl_drm_screen_create(int fd)
    if (pipe_loader_drm_probe_fd(&vscreen->dev, fd, false))
       vscreen->pscreen = pipe_loader_create_screen(vscreen->dev, false);
 
+   if (libva_owned_fd >= 0 && libva_owned_fd != fd)
+      close(fd);
+
    if (!vscreen->pscreen)
       goto release_pipe;
 

src/gallium/frontends/va/context.c

@@ -169,8 +169,16 @@ VA_DRIVER_INIT_FUNC(VADriverContextP ctx)
          FREE(drm_driver_name);
       }
 #endif
-      if(!drv->vscreen)
-         drv->vscreen = vl_drm_screen_create(drm_info->fd);
+      if(!drv->vscreen) {
+         /* VA_DISPLAY_WAYLAND uses the compositor's fd, like VA_DISPLAY_X11 does.
+          * In this case, tell vl_drm_screen_create to consider the DRI_PRIME env
+          * variable to let the user select a different device.
+          * The other display types receive a fd explicitely picked by the application,
+          * so don't try to override them.
+          */
+         bool honor_dri_prime = ctx->display_type == VA_DISPLAY_WAYLAND;
+         drv->vscreen = vl_drm_screen_create(drm_info->fd, honor_dri_prime);
+      }
       break;
    }
 #endif