[libcamera-devel] [PATCH v3 3/8] libcamera: v4l2_device: Add support for META_CAPTURE devices

[Jacopo Mondi]

Hi Laurent,

On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Tue, Feb 26, 2019 at 05:26:36PM +0100, Jacopo Mondi wrote:
> > Add support for devices that provide video meta-data to v4l2_device.cpp
> > and re-arrange bufferType handling in open() method.
> >
> > Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> >  src/libcamera/include/v4l2_device.h |  4 +++
> >  src/libcamera/v4l2_device.cpp       | 38 +++++++++++++++++------------
> >  2 files changed, 27 insertions(+), 15 deletions(-)
> >
> > diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> > index 1d31d1b403bc..52eb6785cc15 100644
> > --- a/src/libcamera/include/v4l2_device.h
> > +++ b/src/libcamera/include/v4l2_device.h
> > @@ -53,6 +53,10 @@ struct V4L2Capability final : v4l2_capability {
> >  		return device_caps() & (V4L2_CAP_VIDEO_CAPTURE |
> >  					V4L2_CAP_VIDEO_CAPTURE_MPLANE);
> >  	}
> > +	bool isMeta() const
> > +	{
> > +		return device_caps() & V4L2_CAP_META_CAPTURE;
> > +	}
> >  	bool isOutput() const
> >  	{
> >  		return device_caps() & (V4L2_CAP_VIDEO_OUTPUT |
>
> Even if you don't introduce support for V4L2_CAP_META_OUTPUT now,
> isCapture() should still return true for V4L2_CAP_META_CAPTURE to ease
> transition later. Don't forget to update the isOutput() and isCapture()
> documentation to not mention video frames anymore, but just output and
> capture.
>

As done in v4, I introduced an isMetaCapture() method, preparing for
an isMetaOutput() one. In this way isCapture() and isOutput() would
refer to video streams only and the bufferType intialization looks
like:

	 * Set buffer type and wait for read notifications on CAPTURE devices
	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
	 */
	if (caps_.isCapture()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
		bufferType_ = caps_.isMultiplanar()
			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
	} else if (caps_.isOutput()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
		bufferType_ = caps_.isMultiplanar()
			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
	} else if (caps_.isMetaCapture()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
	} else if (caps_.isMetaOutput()) {
		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
		bufferType_ = V4L2_BUF_TYPE_META_OUTPUT;
	} else {
		LOG(V4L2, Debug) << "Device is not a supported type";
		return -EINVAL;
	}



> > diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> > index 24e115554a99..8be8af7a2893 100644
> > --- a/src/libcamera/v4l2_device.cpp
> > +++ b/src/libcamera/v4l2_device.cpp
> > @@ -79,6 +79,15 @@ LOG_DEFINE_CATEGORY(V4L2)
> >   * \return True if the device can output video frames
> >   */
> >
> > +/**
> > + * \fn bool V4L2Capability::isMeta()
> > + * \brief Identify if the device is capable of providing video meta-data
> > + *
> > + * FIXME: add support for META_OUTPUT, introduced in Linux v4.20
>
> Maybe \todo ?
>
> s/v4.20/v5.0/
>
> > + *
> > + * \return True if the device can provide video meta-data
> > + */
> > +
> >  /**
> >   * \fn bool V4L2Capability::hasStreaming()
> >   * \brief Determine if the device can perform Streaming I/O
> > @@ -280,33 +289,32 @@ int V4L2Device::open()
> >  		<< "Opened device " << caps_.bus_info() << ": "
> >  		<< caps_.driver() << ": " << caps_.card();
> >
> > -	if (!caps_.isCapture() && !caps_.isOutput()) {
> > -		LOG(V4L2, Debug) << "Device is not a supported type";
> > -		return -EINVAL;
> > -	}
> > -
> >  	if (!caps_.hasStreaming()) {
> >  		LOG(V4L2, Error) << "Device does not support streaming I/O";
> >  		return -EINVAL;
> >  	}
> >
> > -	if (caps_.isCapture())
> > +	/*
> > +	 * Set buffer type and wait for read notifications on CAPTURE devices
> > +	 * (POLLIN), and write notifications for OUTPUT devices (POLLOUT).
> > +	 */
> > +	if (caps_.isCapture()) {
> > +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> >  		bufferType_ = caps_.isMultiplanar()
> >  			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> >  			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> > -	else
> > +	} else if (caps_.isOutput()) {
> > +		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> >  		bufferType_ = caps_.isMultiplanar()
> >  			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> >  			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> > -
> > -	/*
> > -	 *  We wait for Read notifications on CAPTURE devices (POLLIN), and
> > -	 *  Write notifications for OUTPUT devices (POLLOUT).
> > -	 */
> > -	if (caps_.isCapture())
> > +	} else if (caps_.isMeta()) {
> >  		fdEvent_ = new EventNotifier(fd_, EventNotifier::Read);
> > -	else
> > -		fdEvent_ = new EventNotifier(fd_, EventNotifier::Write);
> > +		bufferType_ = V4L2_BUF_TYPE_META_CAPTURE;
> > +	} else {
> > +		LOG(V4L2, Debug) << "Device is not a supported type";
> > +		return -EINVAL;
> > +	}
> >
> >  	fdEvent_->activated.connect(this, &V4L2Device::bufferAvailable);
> >  	fdEvent_->setEnabled(false);
>
> --
> Regards,
>
> Laurent Pinchart
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