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

[Laurent Pinchart]

Hi Jacopo,

On Thu, Feb 28, 2019 at 09:49:53AM +0100, Jacopo Mondi wrote:
> On Wed, Feb 27, 2019 at 07:54:18PM +0200, Laurent Pinchart wrote:
> > 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:

That's confusing. Let's have

isCapture() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_VIDEO_CAPTURE |
	       V4L2_CAP_VIDEO_CAPTURE_MPLANE
isOutput() -> V4L2_CAP_META_OUTPUT | V4L2_CAP_VIDEO_OUTPUT |
	      V4L2_CAP_VIDEO_OUTPUT_MPLANE
isMeta() -> V4L2_CAP_META_CAPTURE | V4L2_CAP_META_OUTPUT
isVideo() -> V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_VIDEO_CAPTURE_MPLANE |
	     V4L2_CAP_VIDEO_OUTPUT | V4L2_CAP_VIDEO_OUTPUT_MPLANE

and you can then also add, if desired,

isMetaCapture() -> isMeta() && 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 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