From 4ca052b4ea621d0002a5e5feace51f60ad5e6b23 Mon Sep 17 00:00:00 2001 From: Laurent Pinchart Date: Mon, 8 Mar 2021 11:31:28 +0100 Subject: [PATCH] media: uvcvideo: Support devices that report an OT as an entity source Some devices reference an output terminal as the source of extension units. This is incorrect, as output terminals only have an input pin, and thus can't be connected to any entity in the forward direction. The resulting topology would cause issues when registering the media controller graph. To avoid this problem, connect the extension unit to the source of the output terminal instead. While at it, and while no device has been reported to be affected by this issue, also handle forward scans where two output terminals would be connected together, and skip the terminals found through such an invalid connection. Reported-and-tested-by: John Nealy Signed-off-by: Laurent Pinchart Signed-off-by: Hans de Goede Signed-off-by: Mauro Carvalho Chehab --- drivers/media/usb/uvc/uvc_driver.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index e55cf02..9a791d8 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -1716,6 +1716,31 @@ static int uvc_scan_chain_forward(struct uvc_video_chain *chain, return -EINVAL; } + /* + * Some devices reference an output terminal as the + * source of extension units. This is incorrect, as + * output terminals only have an input pin, and thus + * can't be connected to any entity in the forward + * direction. The resulting topology would cause issues + * when registering the media controller graph. To + * avoid this problem, connect the extension unit to + * the source of the output terminal instead. + */ + if (UVC_ENTITY_IS_OTERM(entity)) { + struct uvc_entity *source; + + source = uvc_entity_by_id(chain->dev, + entity->baSourceID[0]); + if (!source) { + uvc_dbg(chain->dev, DESCR, + "Can't connect extension unit %u in chain\n", + forward->id); + break; + } + + forward->baSourceID[0] = source->id; + } + list_add_tail(&forward->chain, &chain->entities); if (!found) uvc_dbg_cont(PROBE, " (->"); @@ -1735,6 +1760,13 @@ static int uvc_scan_chain_forward(struct uvc_video_chain *chain, return -EINVAL; } + if (UVC_ENTITY_IS_OTERM(entity)) { + uvc_dbg(chain->dev, DESCR, + "Unsupported connection between output terminals %u and %u\n", + entity->id, forward->id); + break; + } + list_add_tail(&forward->chain, &chain->entities); if (!found) uvc_dbg_cont(PROBE, " (->"); -- 2.7.4