[libcamera-devel] [PATCH 2/2] libcamera: v4l2_device: Add methods to get/set format

[Laurent Pinchart]

Hi Jacopo,

Thank you for the patch.

On Mon, Jan 28, 2019 at 04:11:37PM +0100, Jacopo Mondi wrote:
> Add methods to set and get the image format programmed on a V4L2Device
> for both the single and multi planar use case.
> 
> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> ---
>  src/libcamera/include/v4l2_device.h |  10 +++
>  src/libcamera/v4l2_device.cpp       | 128 ++++++++++++++++++++++++++++
>  2 files changed, 138 insertions(+)
> 
> diff --git a/src/libcamera/include/v4l2_device.h b/src/libcamera/include/v4l2_device.h
> index c70959e..fe54220 100644
> --- a/src/libcamera/include/v4l2_device.h
> +++ b/src/libcamera/include/v4l2_device.h
> @@ -86,10 +86,20 @@ public:
>  	const char *deviceName() const { return caps_.card(); }
>  	const char *busName() const { return caps_.bus_info(); }
>  
> +	int format(V4L2DeviceFormat *fmt);

As an exception to the general rule, I'd rename format() to getFormat()
to follow the V4L2 naming. I won't push hard for this, but I think this
was the general preference of the team as well.

> +	int setFormat(V4L2DeviceFormat *fmt);

How about spelling format in full (here and below) for the function
parameter ?

> +
>  private:
>  	std::string deviceNode_;
>  	int fd_;
>  	V4L2Capability caps_;
> +	enum v4l2_buf_type bufferType_;
> +
> +	int getFormatSingleplane(V4L2DeviceFormat *fmt);
> +	int setFormatSingleplane(V4L2DeviceFormat *fmt);
> +
> +	int getFormatMultiplane(V4L2DeviceFormat *fmt);
> +	int setFormatMultiplane(V4L2DeviceFormat *fmt);
>  };
>  
>  } /* namespace libcamera */
> diff --git a/src/libcamera/v4l2_device.cpp b/src/libcamera/v4l2_device.cpp
> index d6143f2..5c415d0 100644
> --- a/src/libcamera/v4l2_device.cpp
> +++ b/src/libcamera/v4l2_device.cpp
> @@ -227,6 +227,15 @@ int V4L2Device::open()
>  		return -EINVAL;
>  	}
>  
> +	if (caps_.isCapture())
> +		bufferType_ = caps_.isMultiplanar()
> +			    ? V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE
> +			    : V4L2_BUF_TYPE_VIDEO_CAPTURE;
> +	else
> +		bufferType_ = caps_.isMultiplanar()
> +			    ? V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE
> +			    : V4L2_BUF_TYPE_VIDEO_OUTPUT;
> +
>  	return 0;
>  }
>  
> @@ -269,4 +278,123 @@ void V4L2Device::close()
>   * \return The string containing the device location
>   */
>  
> +/**
> + * \brief Retrieve the image format set on the V4L2 device
> + * \return 0 for success, a negative error code otherwise

s/for/on/

> + */
> +int V4L2Device::format(V4L2DeviceFormat *fmt)
> +{
> +	return caps_.isMultiplanar() ? getFormatMultiplane(fmt) :
> +				       getFormatSingleplane(fmt);
> +}
> +
> +/**
> + * \brief Configure an image format on the V4L2 device
> + * \return 0 for success, a negative error code otherwise

s/for/on/

> + */
> +int V4L2Device::setFormat(V4L2DeviceFormat *fmt)
> +{
> +	return caps_.isMultiplanar() ? setFormatMultiplane(fmt) :
> +				       setFormatSingleplane(fmt);
> +}
> +
> +int V4L2Device::getFormatSingleplane(V4L2DeviceFormat *fmt)
> +{
> +	struct v4l2_format v4l2Fmt;

v4l2Format ? Or maybe just fmt if you rename the function parameter to
format ?

You need to initialize v4l2Fmt to 0, that's a requirement of the V4L2
API. = {}; will suffice.

> +	struct v4l2_pix_format *pix = &v4l2Fmt.fmt.pix;
> +	int ret;
> +
> +	v4l2Fmt.type = bufferType_;
> +	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Fmt);

Shouldn't this be VIDIOC_G_FMT ? This outlines a missing test case :-)

> +	if (ret) {
> +		ret = -errno;
> +		LOG(Error) << "Unable to get format: " << strerror(-ret);
> +		return ret;
> +	}
> +
> +	fmt->width = pix->width;
> +	fmt->height = pix->height;
> +	fmt->fourcc = pix->pixelformat;
> +	fmt->planes = 1;
> +	fmt->planesFmt[0].bpl = pix->bytesperline;
> +	fmt->planesFmt[0].size = pix->sizeimage;
> +
> +	return 0;
> +}
> +
> +int V4L2Device::setFormatSingleplane(V4L2DeviceFormat *fmt)
> +{
> +	struct v4l2_format v4l2Fmt;
> +	struct v4l2_pix_format *pix = &v4l2Fmt.fmt.pix;
> +	int ret;
> +
> +	v4l2Fmt.type = bufferType_;
> +	pix->width = fmt->width;
> +	pix->height = fmt->height;
> +	pix->pixelformat = fmt->fourcc;

How about bytesperline and sizeimage ?

> +
> +	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Fmt);
> +	if (ret) {
> +		ret = -errno;
> +		LOG(Error) << "Unable to set format: " << strerror(-ret);
> +		return ret;
> +	}
> +

Shouldn't fmt be updated ?

> +	return 0;
> +}
> +
> +int V4L2Device::getFormatMultiplane(V4L2DeviceFormat *fmt)

The above comments hold for the mplane functions too.

> +{
> +	struct v4l2_format v4l2Fmt;
> +	struct v4l2_pix_format_mplane *pix = &v4l2Fmt.fmt.pix_mp;
> +	int ret;
> +
> +	v4l2Fmt.type = bufferType_;
> +	ret = ioctl(fd_, VIDIOC_G_FMT, &v4l2Fmt);
> +	if (ret) {
> +		ret = -errno;
> +		LOG(Error) << "Unable to get format: " << strerror(-ret);
> +		return ret;
> +	}
> +
> +	fmt->width = pix->width;
> +	fmt->height = pix->height;
> +	fmt->fourcc = pix->pixelformat;
> +	fmt->planes = pix->num_planes;
> +
> +	for (unsigned int i = 0; i < fmt->planes; ++i) {
> +		fmt->planesFmt[i].bpl = pix->plane_fmt[i].bytesperline;
> +		fmt->planesFmt[i].size = pix->plane_fmt[i].sizeimage;
> +	}
> +
> +	return 0;
> +}
> +
> +int V4L2Device::setFormatMultiplane(V4L2DeviceFormat *fmt)
> +{
> +	struct v4l2_format v4l2Fmt;
> +	struct v4l2_pix_format_mplane *pix = &v4l2Fmt.fmt.pix_mp;
> +	int ret;
> +
> +	v4l2Fmt.type = bufferType_;
> +	pix->width = fmt->width;
> +	pix->height = fmt->height;
> +	pix->pixelformat = fmt->fourcc;
> +	pix->num_planes = fmt->planes;
> +
> +	for (unsigned int i = 0; i < pix->num_planes; ++i) {
> +		pix->plane_fmt[i].bytesperline = fmt->planesFmt[i].bpl;
> +		pix->plane_fmt[i].sizeimage = fmt->planesFmt[i].size;
> +	}
> +
> +	ret = ioctl(fd_, VIDIOC_S_FMT, &v4l2Fmt);
> +	if (ret) {
> +		ret = -errno;
> +		LOG(Error) << "Unable to set format: " << strerror(-ret);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +
>  } /* namespace libcamera */

-- 
Regards,

Laurent Pinchart