path: root/drivers/media
diff options
authorOleksij Rempel <linux@rempel-privat.de>2014-02-16 06:59:32 -0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-05-06 07:55:31 -0700
commit63e3c3d7bef11c917646fb6babb81c72d0aa4949 (patch)
treea5364d1948465738a6bde216034b9659c59b134e /drivers/media
parent65cadc88d143361a60951b01ae32ec6b9bc88f6b (diff)
media: uvcvideo: Do not use usb_set_interface on bulk EP
commit b1e43f232698274871e1358c276d7b0242a7d607 upstream. The UVC specification uses alternate setting selection to notify devices of stream start/stop. This breaks when using bulk-based devices, as the video streaming interface has a single alternate setting in that case, making video stream start and video stream stop events to appear identical to the device. Bulk-based devices are thus not well supported by UVC. The webcam built in the Asus Zenbook UX302LA ignores the set interface request and will keep the video stream enabled when the driver tries to stop it. If USB autosuspend is enabled the device will then be suspended and will crash, requiring a cold reboot. USB trace capture showed that Windows sends a CLEAR_FEATURE(HALT) request to the bulk endpoint when stopping the stream instead of selecting alternate setting 0. The camera then behaves correctly, and thus seems to require that behaviour. Replace selection of alternate setting 0 with clearing of the endpoint halt feature at video stream stop for bulk-based devices. Let's refrain from blaming Microsoft this time, as it's not clear whether this Windows-specific but USB-compliant behaviour was specifically developed to handle bulkd-based UVC devices, or if the camera just took advantage of it. Signed-off-by: Oleksij Rempel <linux@rempel-privat.de> Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/media')
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/media/usb/uvc/uvc_video.c b/drivers/media/usb/uvc/uvc_video.c
index 3394c3432011..e1c5bf3ea112 100644
--- a/drivers/media/usb/uvc/uvc_video.c
+++ b/drivers/media/usb/uvc/uvc_video.c
@@ -1846,7 +1846,25 @@ int uvc_video_enable(struct uvc_streaming *stream, int enable)
if (!enable) {
uvc_uninit_video(stream, 1);
- usb_set_interface(stream->dev->udev, stream->intfnum, 0);
+ if (stream->intf->num_altsetting > 1) {
+ usb_set_interface(stream->dev->udev,
+ stream->intfnum, 0);
+ } else {
+ /* UVC doesn't specify how to inform a bulk-based device
+ * when the video stream is stopped. Windows sends a
+ * CLEAR_FEATURE(HALT) request to the video streaming
+ * bulk endpoint, mimic the same behaviour.
+ */
+ unsigned int epnum = stream->header.bEndpointAddress
+ unsigned int dir = stream->header.bEndpointAddress
+ unsigned int pipe;
+ pipe = usb_sndbulkpipe(stream->dev->udev, epnum) | dir;
+ usb_clear_halt(stream->dev->udev, pipe);
+ }
uvc_queue_enable(&stream->queue, 0);
return 0;