[libcamera-devel] [PATCH v5 1/3] libcamera: v4l2_videodevice: Add a dequeue timer
Umang Jain
umang.jain at ideasonboard.com
Wed Apr 6 16:47:41 CEST 2022
Hi Naush,
On 4/6/22 18:05, Naushir Patuck via libcamera-devel wrote:
> Add a timer that gets reset on every buffer dequeue event. If the timeout
> expires, optionally call a slot in the pipeline handler to handle this
> condition. This may be useful in detecting and handling stalls in either the
> hardware or device driver.
>
> Signed-off-by: Naushir Patuck <naush at raspberrypi.com>
> Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> ---
> include/libcamera/internal/v4l2_videodevice.h | 10 ++++
> src/libcamera/v4l2_videodevice.cpp | 53 +++++++++++++++++++
> 2 files changed, 63 insertions(+)
>
> diff --git a/include/libcamera/internal/v4l2_videodevice.h b/include/libcamera/internal/v4l2_videodevice.h
> index cfeae7bd6c52..9c9493cc16ed 100644
> --- a/include/libcamera/internal/v4l2_videodevice.h
> +++ b/include/libcamera/internal/v4l2_videodevice.h
> @@ -20,7 +20,9 @@
> #include <libcamera/base/class.h>
> #include <libcamera/base/log.h>
> #include <libcamera/base/signal.h>
> +#include <libcamera/base/timer.h>
> #include <libcamera/base/unique_fd.h>
> +#include <libcamera/base/utils.h>
>
> #include <libcamera/color_space.h>
> #include <libcamera/framebuffer.h>
> @@ -217,6 +219,9 @@ public:
> int streamOn();
> int streamOff();
>
> + void setDequeueTimeout(utils::Duration timeout);
> + Signal<> dequeueTimeout;
> +
> static std::unique_ptr<V4L2VideoDevice>
> fromEntityName(const MediaDevice *media, const std::string &entity);
>
> @@ -253,6 +258,8 @@ private:
> void bufferAvailable();
> FrameBuffer *dequeueBuffer();
>
> + void watchdogExpired();
> +
> V4L2Capability caps_;
> V4L2DeviceFormat format_;
> const PixelFormatInfo *formatInfo_;
> @@ -266,6 +273,9 @@ private:
> EventNotifier *fdBufferNotifier_;
>
> State state_;
> +
> + Timer watchdog_;
> + utils::Duration watchdogDuration_;
This ended up being used un-initialised which in turn polluted the log:
https://paste.debian.net/1236996/
I have posted a patch "libcamera: v4l2_videodevice: Fix uninitialised
watchdogDuration_" to fix it
> };
>
> class V4L2M2MDevice
> diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
> index 0830be80c553..c3a1b6c42e19 100644
> --- a/src/libcamera/v4l2_videodevice.cpp
> +++ b/src/libcamera/v4l2_videodevice.cpp
> @@ -539,6 +539,7 @@ V4L2VideoDevice::V4L2VideoDevice(const std::string &deviceNode)
> V4L2VideoDevice::V4L2VideoDevice(const MediaEntity *entity)
> : V4L2VideoDevice(entity->deviceNode())
> {
> + watchdog_.timeout.connect(this, &V4L2VideoDevice::watchdogExpired);
> }
>
> V4L2VideoDevice::~V4L2VideoDevice()
> @@ -1726,6 +1727,9 @@ 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;
> @@ -1828,6 +1832,8 @@ int V4L2VideoDevice::streamOn()
> }
>
> state_ = State::Streaming;
> + if (watchdogDuration_.count())
> + watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(watchdogDuration_));
>
> return 0;
> }
> @@ -1852,6 +1858,9 @@ int V4L2VideoDevice::streamOff()
> if (state_ != State::Streaming && queuedBuffers_.empty())
> return 0;
>
> + if (watchdogDuration_.count())
> + watchdog_.stop();
> +
> ret = ioctl(VIDIOC_STREAMOFF, &bufferType_);
> if (ret < 0) {
> LOG(V4L2, Error)
> @@ -1879,6 +1888,50 @@ int V4L2VideoDevice::streamOff()
> return 0;
> }
>
> +/**
> + * \brief Set the dequeue timeout value
> + * \param[in] timeout The timeout value to be used
> + *
> + * Sets a timeout value, given by \a timeout, that will be used by a watchdog
> + * timer to ensure buffer dequeue events are periodically occurring when the
> + * device is streaming. The watchdog timer is only active when the device is
> + * streaming, so it is not necessary to disable it when the device stops
> + * streaming. The timeout value can be safely updated at any time.
> + *
> + * If the timer expires, the \ref V4L2VideoDevice::dequeueTimeout signal is
> + * emitted. This can typically be used by pipeline handlers to be notified of
> + * stalled devices.
> + *
> + * Set \a timeout to 0 to disable the watchdog timer.
> + */
> +void V4L2VideoDevice::setDequeueTimeout(utils::Duration timeout)
> +{
> + watchdogDuration_ = timeout;
> +
> + watchdog_.stop();
> + if (watchdogDuration_.count() && state_ == State::Streaming)
> + watchdog_.start(std::chrono::duration_cast<std::chrono::milliseconds>(timeout));
> +}
> +
> +/**
> + * \var V4L2VideoDevice::dequeueTimeout
> + * \brief A Signal emitted when the dequeue watchdog timer expires
> + */
> +
> +/**
> + * \brief Slot to handle an expired dequeue timer
> + *
> + * When this slot is called, the time between successive dequeue events is over
> + * the required timeout. Emit the \ref V4L2VideoDevice::dequeueTimeout signal.
> + */
> +void V4L2VideoDevice::watchdogExpired()
> +{
> + LOG(V4L2, Warning)
> + << "Dequeue timer of " << watchdogDuration_ << " has expired!";
> +
> + dequeueTimeout.emit();
> +}
> +
> /**
> * \brief Create a new video device instance from \a entity in media device
> * \a media
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