hwcontext_vaapi: Don't require a render node when deriving from DRMvaapi/drm-render-node

The V4L2 driver does not actually have an associated DRM device at all, so
users work around the requirement by giving libva an unrelated display-only
device instead (which is fine, because it doesn't actually do anything with
that device).  This was broken by bc9b6358fb7315c0173de322472641766f6289da
forcing a render node, because the display-only device did not have a
matching render node to use.  Fix that by just passing through the original
non-render DRM fd if we can't find a render node.

Reported-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>

1 files changed, 14 insertions, 12 deletions

diff --git a/libavutil/hwcontext_vaapi.c b/libavutil/hwcontext_vaapi.c
index 38bdeb7820..b576447407 100644
--- a/libavutil/hwcontext_vaapi.c
+++ b/libavutil/hwcontext_vaapi.c
@@ -1677,20 +1677,22 @@ static int vaapi_device_derive(AVHWDeviceContext *ctx,
             } else {
                 render_node = drmGetRenderDeviceNameFromFd(src_hwctx->fd);
                 if (!render_node) {
-                    av_log(ctx, AV_LOG_ERROR, "Failed to find a render node "
-                           "matching the DRM device.\n");
-                    return AVERROR(ENODEV);
-                }
-                fd = open(render_node, O_RDWR);
-                if (fd < 0) {
-                    av_log(ctx, AV_LOG_ERROR, "Failed to open render node %s"
-                           "matching the DRM device.\n", render_node);
+                    av_log(ctx, AV_LOG_VERBOSE, "Using non-render node "
+                           "because no associated render node was found.\n");
+                    fd = src_hwctx->fd;
+                } else {
+                    fd = open(render_node, O_RDWR);
+                    if (fd < 0) {
+                        av_log(ctx, AV_LOG_VERBOSE, "Using non-render node "
+                               "because render node failed to open.\n");
+                        fd = src_hwctx->fd;
+                    } else {
+                        av_log(ctx, AV_LOG_VERBOSE, "Using render node %s "
+                               "in place of non-render DRM device.\n",
+                               render_node);
+                    }
                     free(render_node);
-                    return AVERROR(errno);
                 }
-                av_log(ctx, AV_LOG_VERBOSE, "Using render node %s in place "
-                       "of non-render DRM device.\n", render_node);
-                free(render_node);
             }
         }
 #else