From: Shawn Nematbakhsh <shawnn@google.com>
To: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@redhat.com>,
linux-media@vger.kernel.org, linux-kernel@vger.kernel.org,
shawnn@chromium.org
Subject: [PATCH] [media] uvcvideo: Retry usb_submit_urb on -EPERM return
Date: Tue, 23 Apr 2013 17:41:13 -0700 [thread overview]
Message-ID: <1366764073-9633-1-git-send-email-shawnn@google.com> (raw)
From: Shawn Nematbakhsh <shawnn@chromium.org>
While usb_kill_urb is in progress, calls to usb_submit_urb will fail
with -EPERM (documented in Documentation/usb/URB.txt). The UVC driver
does not correctly handle this case -- there is no synchronization
between uvc_v4l2_open / uvc_status_start and uvc_v4l2_release /
uvc_status_stop.
This patch adds a retry / timeout when uvc_status_open / usb_submit_urb
returns -EPERM. This usually means that usb_kill_urb is in progress, and
we just need to wait a while.
Signed-off-by: Shawn Nematbakhsh <shawnn@chromium.org>
---
drivers/media/usb/uvc/uvc_v4l2.c | 10 +++++++++-
drivers/media/usb/uvc/uvcvideo.h | 1 +
2 files changed, 10 insertions(+), 1 deletion(-)
diff --git a/drivers/media/usb/uvc/uvc_v4l2.c b/drivers/media/usb/uvc/uvc_v4l2.c
index b2dc326..f1498a8 100644
--- a/drivers/media/usb/uvc/uvc_v4l2.c
+++ b/drivers/media/usb/uvc/uvc_v4l2.c
@@ -479,6 +479,7 @@ static int uvc_v4l2_open(struct file *file)
{
struct uvc_streaming *stream;
struct uvc_fh *handle;
+ unsigned long timeout;
int ret = 0;
uvc_trace(UVC_TRACE_CALLS, "uvc_v4l2_open\n");
@@ -499,7 +500,14 @@ static int uvc_v4l2_open(struct file *file)
}
if (atomic_inc_return(&stream->dev->users) == 1) {
- ret = uvc_status_start(stream->dev);
+ timeout = jiffies + msecs_to_jiffies(UVC_STATUS_START_TIMEOUT);
+ /* -EPERM means stop in progress, wait for completion */
+ do {
+ ret = uvc_status_start(stream->dev);
+ if (ret == -EPERM)
+ usleep_range(5000, 6000);
+ } while (ret == -EPERM && time_before(jiffies, timeout));
+
if (ret < 0) {
atomic_dec(&stream->dev->users);
usb_autopm_put_interface(stream->dev->intf);
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index af505fd..a47e1d3 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -122,6 +122,7 @@
#define UVC_CTRL_CONTROL_TIMEOUT 300
#define UVC_CTRL_STREAMING_TIMEOUT 5000
+#define UVC_STATUS_START_TIMEOUT 100
/* Maximum allowed number of control mappings per device */
#define UVC_MAX_CONTROL_MAPPINGS 1024
--
1.7.12.4
next reply other threads:[~2013-04-24 0:41 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-24 0:41 Shawn Nematbakhsh [this message]
-- strict thread matches above, loose matches on Subject: below --
2013-04-24 0:42 [PATCH] [media] uvcvideo: Retry usb_submit_urb on -EPERM return Shawn Nematbakhsh
2013-04-29 20:34 ` Laurent Pinchart
2013-05-03 23:00 ` Shawn Nematbakhsh
2013-05-07 11:14 ` Laurent Pinchart
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1366764073-9633-1-git-send-email-shawnn@google.com \
--to=shawnn@google.com \
--cc=laurent.pinchart@ideasonboard.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-media@vger.kernel.org \
--cc=mchehab@redhat.com \
--cc=shawnn@chromium.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox