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

[Laurent Pinchart]

Hi Naush,

Thank you for the patch.

On Thu, May 05, 2022 at 09:48:24AM +0100, Naushir Patuck via libcamera-devel 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>

Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>

> ---
>  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));
>  }
>  

-- 
Regards,

Laurent Pinchart