Don't fall back to the generic hwaccel for DRM_PRIME formats

app/streaming/video/ffmpeg.cpp

@@ -1049,8 +1049,15 @@ IFFmpegRenderer* FFmpegVideoDecoder::createHwAccelRenderer(const AVCodecHWConfig
             return nullptr;
 
         default:
+            if (hwDecodeCfg->pix_fmt != AV_PIX_FMT_DRM_PRIME) {
                 return new GenericHwAccelRenderer(hwDecodeCfg->device_type);
             }
+            else {
+                // We already handle unknown devices types that
+                // output DRM_PRIME frames above in pass 0.
+                return nullptr;
+            }
+        }
     }
     else {
         SDL_assert(false);