From: Sumit Semwal sumit.semwal@linaro.org
This patch has been added to the stable tree. If you have any objections, please let us know.
===============
[ Upstream commit e950267ab802c8558f1100eafd4087fd039ad634 ]
Some devices have invalid baSourceID references, causing uvc_scan_chain() to fail, but if we just take the entities we can find and put them together in the most sensible chain we can think of, turns out they do work anyway. Note: This heuristic assumes there is a single chain.
At the time of writing, devices known to have such a broken chain are - Acer Integrated Camera (5986:055a) - Realtek rtl157a7 (0bda:57a7)
Signed-off-by: Henrik Ingo henrik.ingo@avoinelama.fi Signed-off-by: Laurent Pinchart laurent.pinchart@ideasonboard.com Signed-off-by: Mauro Carvalho Chehab mchehab@s-opensource.com Signed-off-by: Sasha Levin alexander.levin@microsoft.com --- drivers/media/usb/uvc/uvc_driver.c | 118 +++++++++++++++++++++++++++++++++++-- 1 file changed, 112 insertions(+), 6 deletions(-)
diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c index 5970dd6a1c1c..a41a4f6a51b2 100644 --- a/drivers/media/usb/uvc/uvc_driver.c +++ b/drivers/media/usb/uvc/uvc_driver.c @@ -1574,6 +1574,114 @@ static const char *uvc_print_chain(struct uvc_video_chain *chain) return buffer; }
+static struct uvc_video_chain *uvc_alloc_chain(struct uvc_device *dev) +{ + struct uvc_video_chain *chain; + + chain = kzalloc(sizeof(*chain), GFP_KERNEL); + if (chain == NULL) + return NULL; + + INIT_LIST_HEAD(&chain->entities); + mutex_init(&chain->ctrl_mutex); + chain->dev = dev; + v4l2_prio_init(&chain->prio); + + return chain; +} + +/* + * Fallback heuristic for devices that don't connect units and terminals in a + * valid chain. + * + * Some devices have invalid baSourceID references, causing uvc_scan_chain() + * to fail, but if we just take the entities we can find and put them together + * in the most sensible chain we can think of, turns out they do work anyway. + * Note: This heuristic assumes there is a single chain. + * + * At the time of writing, devices known to have such a broken chain are + * - Acer Integrated Camera (5986:055a) + * - Realtek rtl157a7 (0bda:57a7) + */ +static int uvc_scan_fallback(struct uvc_device *dev) +{ + struct uvc_video_chain *chain; + struct uvc_entity *iterm = NULL; + struct uvc_entity *oterm = NULL; + struct uvc_entity *entity; + struct uvc_entity *prev; + + /* + * Start by locating the input and output terminals. We only support + * devices with exactly one of each for now. + */ + list_for_each_entry(entity, &dev->entities, list) { + if (UVC_ENTITY_IS_ITERM(entity)) { + if (iterm) + return -EINVAL; + iterm = entity; + } + + if (UVC_ENTITY_IS_OTERM(entity)) { + if (oterm) + return -EINVAL; + oterm = entity; + } + } + + if (iterm == NULL || oterm == NULL) + return -EINVAL; + + /* Allocate the chain and fill it. */ + chain = uvc_alloc_chain(dev); + if (chain == NULL) + return -ENOMEM; + + if (uvc_scan_chain_entity(chain, oterm) < 0) + goto error; + + prev = oterm; + + /* + * Add all Processing and Extension Units with two pads. The order + * doesn't matter much, use reverse list traversal to connect units in + * UVC descriptor order as we build the chain from output to input. This + * leads to units appearing in the order meant by the manufacturer for + * the cameras known to require this heuristic. + */ + list_for_each_entry_reverse(entity, &dev->entities, list) { + if (entity->type != UVC_VC_PROCESSING_UNIT && + entity->type != UVC_VC_EXTENSION_UNIT) + continue; + + if (entity->num_pads != 2) + continue; + + if (uvc_scan_chain_entity(chain, entity) < 0) + goto error; + + prev->baSourceID[0] = entity->id; + prev = entity; + } + + if (uvc_scan_chain_entity(chain, iterm) < 0) + goto error; + + prev->baSourceID[0] = iterm->id; + + list_add_tail(&chain->list, &dev->chains); + + uvc_trace(UVC_TRACE_PROBE, + "Found a video chain by fallback heuristic (%s).\n", + uvc_print_chain(chain)); + + return 0; + +error: + kfree(chain); + return -EINVAL; +} + /* * Scan the device for video chains and register video devices. * @@ -1596,15 +1704,10 @@ static int uvc_scan_device(struct uvc_device *dev) if (term->chain.next || term->chain.prev) continue;
- chain = kzalloc(sizeof(*chain), GFP_KERNEL); + chain = uvc_alloc_chain(dev); if (chain == NULL) return -ENOMEM;
- INIT_LIST_HEAD(&chain->entities); - mutex_init(&chain->ctrl_mutex); - chain->dev = dev; - v4l2_prio_init(&chain->prio); - term->flags |= UVC_ENTITY_FLAG_DEFAULT;
if (uvc_scan_chain(chain, term) < 0) { @@ -1618,6 +1721,9 @@ static int uvc_scan_device(struct uvc_device *dev) list_add_tail(&chain->list, &dev->chains); }
+ if (list_empty(&dev->chains)) + uvc_scan_fallback(dev); + if (list_empty(&dev->chains)) { uvc_printk(KERN_INFO, "No valid video chain found.\n"); return -1;