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

[Jacopo Mondi]

Hi Laurent,

On Thu, Feb 28, 2019 at 07:25:49PM +0200, Laurent Pinchart wrote:
> 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);
> >

[snip]

> > 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()
> ...
>

I think the code below here, which is the only place where those
functions are used would become less nice if this case.

Those functions are only used to assign bufferType_ and fdEvent_,
let's keep it straightforward as the below series of if/else


> >
> > 	 * 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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