Don't handle the first output terminal in a chain in a special way. Use uvc_scan_chain_entity() like for all other entities, making the chain scan code more generic. Signed-off-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> Index: v4l-dvb-mc/linux/drivers/media/video/uvc/uvc_driver.c =================================================================== --- v4l-dvb-mc.orig/linux/drivers/media/video/uvc/uvc_driver.c +++ v4l-dvb-mc/linux/drivers/media/video/uvc/uvc_driver.c @@ -1256,13 +1256,12 @@ static int uvc_scan_chain_entity(struct break; case UVC_TT_STREAMING: - if (uvc_trace_param & UVC_TRACE_PROBE) - printk(" <- IT %d\n", entity->id); - - if (!UVC_ENTITY_IS_ITERM(entity)) { - uvc_trace(UVC_TRACE_DESCR, "Unsupported input " - "terminal %u.\n", entity->id); - return -1; + if (UVC_ENTITY_IS_ITERM(entity)) { + if (uvc_trace_param & UVC_TRACE_PROBE) + printk(" <- IT %d\n", entity->id); + } else { + if (uvc_trace_param & UVC_TRACE_PROBE) + printk(" OT %d", entity->id); } break; @@ -1342,10 +1341,11 @@ static int uvc_scan_chain_forward(struct } static int uvc_scan_chain_backward(struct uvc_video_chain *chain, - struct uvc_entity *entity) + struct uvc_entity **_entity) { + struct uvc_entity *entity = *_entity; struct uvc_entity *term; - int id = -1, i; + int id = -EINVAL, i; switch (UVC_ENTITY_TYPE(entity)) { case UVC_VC_EXTENSION_UNIT: @@ -1389,34 +1389,49 @@ static int uvc_scan_chain_backward(struc id = 0; break; + + case UVC_ITT_VENDOR_SPECIFIC: + case UVC_ITT_CAMERA: + case UVC_ITT_MEDIA_TRANSPORT_INPUT: + case UVC_OTT_VENDOR_SPECIFIC: + case UVC_OTT_DISPLAY: + case UVC_OTT_MEDIA_TRANSPORT_OUTPUT: + case UVC_TT_STREAMING: + id = UVC_ENTITY_IS_OTERM(entity) ? entity->output.bSourceID : 0; + break; + } + + if (id <= 0) { + *_entity = NULL; + return id; + } + + entity = uvc_entity_by_id(chain->dev, id); + if (entity == NULL) { + uvc_trace(UVC_TRACE_DESCR, "Found reference to " + "unknown entity %d.\n", id); + return -EINVAL; } - return id; + *_entity = entity; + return 0; } static int uvc_scan_chain(struct uvc_video_chain *chain, - struct uvc_entity *oterm) + struct uvc_entity *term) { struct uvc_entity *entity, *prev; - int id; - entity = oterm; - list_add_tail(&entity->chain, &chain->entities); - uvc_trace(UVC_TRACE_PROBE, "Scanning UVC chain: OT %d", entity->id); + uvc_trace(UVC_TRACE_PROBE, "Scanning UVC chain:"); - id = entity->output.bSourceID; - while (id != 0) { - prev = entity; - entity = uvc_entity_by_id(chain->dev, id); - if (entity == NULL) { - uvc_trace(UVC_TRACE_DESCR, "Found reference to " - "unknown entity %d.\n", id); - return -EINVAL; - } + entity = term; + prev = NULL; + while (entity != NULL) { + /* Entity must not be part of an existing chain */ if (entity->chain.next || entity->chain.prev) { uvc_trace(UVC_TRACE_DESCR, "Found reference to " - "entity %d already in chain.\n", id); + "entity %d already in chain.\n", entity->id); return -EINVAL; } @@ -1428,14 +1443,10 @@ static int uvc_scan_chain(struct uvc_vid if (uvc_scan_chain_forward(chain, entity, prev) < 0) return -EINVAL; - /* Stop when a terminal is found. */ - if (UVC_ENTITY_IS_TERM(entity)) - break; - /* Backward scan */ - id = uvc_scan_chain_backward(chain, entity); - if (id < 0) - return id; + prev = entity; + if (uvc_scan_chain_backward(chain, &entity) < 0) + return -EINVAL; } return 0; -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html