[libcamera-devel] [PATCH v1] v4l2_videodevice: Disable the watchdog timer when no buffers are queued

[David Plowman]

Hi Naush

Thanks for fixing this!

On Thu, 5 May 2022 at 09:48, Naushir Patuck via libcamera-devel
<libcamera-devel at lists.libcamera.org> wrote:
>
> Only enable/reset the watchdog timer when there are buffers queued in the V4L2
> device. Otherwise, we may trigger spurious warnings when the watchdog times out
> even if there are no buffers queued in the device.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>

Works for me, and on the Picamera2 auto test machine:

Tested-by: David Plowman <david.plowman at raspberrypi.com>

Thanks!
David

> ---
>  src/libcamera/v4l2_videodevice.cpp | 22 +++++++++++++++-------
>  1 file changed, 15 insertions(+), 7 deletions(-)
>
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index 5b4637b1a39e..430715afd554 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -1662,8 +1662,11 @@ int V4L2VideoDevice::queueBuffer(FrameBuffer *buffer)
>                 return ret;
>         }
>
> -       if (queuedBuffers_.empty())
> +       if (queuedBuffers_.empty()) {
>                 fdBufferNotifier_->setEnabled(true);
> +               if (watchdogDuration_)
> +                       watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(watchdogDuration_));
> +       }
>
>         queuedBuffers_[buf.index] = buffer;
>
> @@ -1742,16 +1745,21 @@ FrameBuffer *V4L2VideoDevice::dequeueBuffer()
>                 return nullptr;
>         }
>
> -       if (watchdogDuration_.count())
> -               watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(watchdogDuration_));
> -
>         cache_->put(buf.index);
>
>         FrameBuffer *buffer = it->second;
>         queuedBuffers_.erase(it);
>
> -       if (queuedBuffers_.empty())
> +       if (queuedBuffers_.empty()) {
>                 fdBufferNotifier_->setEnabled(false);
> +               watchdog_.stop();
> +       } else if (watchdogDuration_) {
> +               /*
> +                * Restart the watchdog timer if there are buffers still queued
> +                * in the device.
> +                */
> +               watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(watchdogDuration_));
> +       }
>
>         buffer->metadata_.status = buf.flags & V4L2_BUF_FLAG_ERROR
>                                  ? FrameMetadata::FrameError
> @@ -1847,7 +1855,7 @@ int V4L2VideoDevice::streamOn()
>         }
>
>         state_ = State::Streaming;
> -       if (watchdogDuration_.count())
> +       if (watchdogDuration_ && !queuedBuffers_.empty())
>                 watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(watchdogDuration_));
>
>         return 0;
> @@ -1924,7 +1932,7 @@ void V4L2VideoDevice::setDequeueTimeout(utils::Duration timeout)
>         watchdogDuration_ = timeout;
>
>         watchdog_.stop();
> -       if (watchdogDuration_.count() && state_ == State::Streaming)
> +       if (watchdogDuration_ && state_ == State::Streaming && !queuedBuffers_.empty())
>                 watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(timeout));
>  }
>
> --
> 2.25.1
>