modesetting: get unaccelerated shadowfb modesetting working with gbm buffers only

Signed-off-by: stefan11111 <[email protected]>

Author: stefan11111

hw/xfree86/drivers/video/modesetting/driver.c

@@ -1690,7 +1690,7 @@ modesetCreateScreenResources(ScreenPtr pScreen)
     if (!ms->drmmode.sw_cursor)
         drmmode_map_cursor_bos(pScrn, &ms->drmmode);
 
-    if (!ms->drmmode.gbm) {
+    if (ms->drmmode.shadow_enable) {
         pixels = drmmode_map_front_bo(&ms->drmmode);
         if (!pixels)
             return FALSE;

hw/xfree86/drivers/video/modesetting/drmmode_display.c

@@ -1157,7 +1157,7 @@ drmmode_bo_backing_bo_from_fd(drmmode_ptr drmmode, drmmode_bo *bo, int fd_handle
                                                  .stride = pitch,
                                                  .format = format,
                                                 };
-        /* Do we need scanout, even though this is a backing bo? */
+        /* XXX Do we need scanout here? Will this backing bo ever be scanned out? XXX */
         struct gbm_bo *ret = gbm_bo_import(drmmode->gbm, GBM_BO_IMPORT_FD, &import_data, GBM_BO_USE_RENDERING);
         if (ret) {
             bo->width = width;
@@ -1296,21 +1296,14 @@ drmmode_create_bpp_probe_bo(drmmode_ptr drmmode, drmmode_bo *bo,
     if (gbm_dev) {
         uint32_t format = drmmode_gbm_format_for_depth(depth);
 
-        /* First try writeable buffer */
-        bo->gbm = gbm_bo_create(gbm_dev, width, height, format,
+        bo->gbm = gbm_bo_create(gbm_dev, width, height,
+                                /* libgbm expects this for dumb scanout buffers for some reason */
+                                (format == GBM_FORMAT_ARGB8888) ? GBM_FORMAT_XRGB8888 : format,
                                 GBM_BO_USE_SCANOUT | GBM_BO_USE_WRITE);
         if (bo->gbm) {
             bo->used_modifiers = FALSE;
             return TRUE;
         }
-
-        /* Then try non-writeable buffer */
-        bo->gbm = gbm_bo_create(gbm_dev, width, height, format,
-                                GBM_BO_USE_RENDERING | GBM_BO_USE_SCANOUT);
-        if (bo->gbm) {
-            bo->used_modifiers = FALSE;
-            return TRUE;
-        }
     }
 #endif
 
@@ -1355,6 +1348,17 @@ drmmode_create_front_bo(drmmode_ptr drmmode, drmmode_bo *bo,
                 return TRUE;
             }
         }
+    } else if (drmmode->shadow_enable && drmmode->gbm) {
+        /* We don't need glamor if modifiers aren't used */
+        bo->gbm = gbm_bo_create(drmmode->gbm, width, height,
+                                /* libgbm expects this for dumb scanout buffers for some reason */
+                                (format == GBM_FORMAT_ARGB8888) ? GBM_FORMAT_XRGB8888 : format,
+                                GBM_BO_USE_WRITE | GBM_BO_USE_SCANOUT |
+                                GBM_BO_USE_FRONT_RENDERING);
+        if (bo->gbm) {
+            bo->used_modifiers = FALSE;
+            return TRUE;
+        }
     }
 #endif