Patch "uvcvideo: uvc_scan_fallback() for webcams with broken chain" has been added to the 4.4-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    uvcvideo: uvc_scan_fallback() for webcams with broken chain

to the 4.4-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     uvcvideo-uvc_scan_fallback-for-webcams-with-broken-chain.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Mar 28 13:59:27 CEST 2017
From: Sumit Semwal <sumit.semwal@linaro.org>
Date: Sat, 25 Mar 2017 21:48:16 +0530
Subject: uvcvideo: uvc_scan_fallback() for webcams with broken chain
To: stable@vger.kernel.org
Cc: Henrik Ingo <henrik.ingo@avoinelama.fi>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Mauro Carvalho Chehab <mchehab@s-opensource.com>, Sasha Levin <alexander.levin@verizon.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Sumit Semwal <sumit.semwal@linaro.org>
Message-ID: <1490458699-24484-17-git-send-email-sumit.semwal@linaro.org>

From: Sumit Semwal <sumit.semwal@linaro.org>


From: Henrik Ingo <henrik.ingo@avoinelama.fi>

[ 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@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/media/usb/uvc/uvc_driver.c |  118 +++++++++++++++++++++++++++++++++++--
 1 file changed, 112 insertions(+), 6 deletions(-)

--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -1595,6 +1595,114 @@ static const char *uvc_print_chain(struc
 	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.
  *
@@ -1617,15 +1725,10 @@ static int uvc_scan_device(struct uvc_de
 		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) {
@@ -1639,6 +1742,9 @@ static int uvc_scan_device(struct uvc_de
 		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;


Patches currently in stable-queue which might be from sumit.semwal@linaro.org are

queue-4.4/pci-add-comments-about-rom-bar-updating.patch
queue-4.4/acpi-blacklist-make-dell-latitude-3350-ethernet-work.patch
queue-4.4/s390-zcrypt-introduce-cex6-toleration.patch
queue-4.4/block-allow-write_same-commands-with-the-sg_io-ioctl.patch
queue-4.4/pci-do-any-vf-bar-updates-before-enabling-the-bars.patch
queue-4.4/x86-hyperv-handle-unknown-nmis-on-one-cpu-when-unknown_nmi_panic.patch
queue-4.4/serial-8250_pci-detach-low-level-driver-during-pci-error-recovery.patch
queue-4.4/xen-do-not-re-use-pirq-number-cached-in-pci-device-msi-msg-data.patch
queue-4.4/pci-separate-vf-bar-updates-from-standard-bar-updates.patch
queue-4.4/pci-ignore-bar-updates-on-virtual-functions.patch
queue-4.4/pci-update-bars-using-property-bits-appropriate-for-type.patch
queue-4.4/vfio-spapr-postpone-allocation-of-userspace-version-of-tce-table.patch
queue-4.4/pci-don-t-update-vf-bars-while-vf-memory-space-is-enabled.patch
queue-4.4/igb-workaround-for-igb-i210-firmware-issue.patch
queue-4.4/pci-remove-pci_resource_bar-and-pci_iov_resource_bar.patch
queue-4.4/pci-decouple-ioresource_rom_enable-and-pci_rom_address_enable.patch
queue-4.4/acpi-blacklist-add-_rev-quirks-for-dell-precision-5520-and-3520.patch
queue-4.4/igb-add-i211-to-i210-phy-workaround.patch
queue-4.4/uvcvideo-uvc_scan_fallback-for-webcams-with-broken-chain.patch