[libcamera-devel] [PATCH 1/3] libcamera: v4l2_subdevice: Implement ENUM_FRAME_SIZES

[Laurent Pinchart]

Hi Jacopo,

On Mon, Feb 25, 2019 at 10:44:35AM +0100, Jacopo Mondi wrote:
> On Mon, Feb 25, 2019 at 10:28:33AM +0100, Jacopo Mondi wrote:
> > On Thu, Feb 21, 2019 at 04:31:56PM +0100, Niklas Söderlund wrote:
> >> On 2019-02-19 17:56:18 +0100, Jacopo Mondi wrote:
> >>> Implement enumFormat() methods to enumerate the available image
> >>> resolutions on the subdevice.
> >>>
> >>> Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> >>> ---
> >>>  src/libcamera/include/v4l2_subdevice.h | 11 ++++
> >>>  src/libcamera/v4l2_subdevice.cpp       | 90 ++++++++++++++++++++++++++
> >>>  2 files changed, 101 insertions(+)
> >>>
> >>> diff --git a/src/libcamera/include/v4l2_subdevice.h b/src/libcamera/include/v4l2_subdevice.h
> >>> index 82fa6685ab52..c7045776555c 100644
> >>> --- a/src/libcamera/include/v4l2_subdevice.h
> >>> +++ b/src/libcamera/include/v4l2_subdevice.h
> >>> @@ -14,6 +14,16 @@ namespace libcamera {
> >>>  class MediaEntity;
> >>>  struct Rectangle;
> >>>
> >>> +struct V4L2SubdeviceFormatEnum {
> >>> +	unsigned int index;
> >>> +	uint32_t mbus_code;
> >>> +
> >>> +	uint32_t minWidth;
> >>> +	uint32_t maxWidth;
> >>> +	uint32_t minHeight;
> >>> +	uint32_t maxHeight;
> >>> +};
> >>> +
> >>>  struct V4L2SubdeviceFormat {
> >>>  	uint32_t mbus_code;
> >>>  	uint32_t width;
> >>> @@ -36,6 +46,7 @@ public:
> >>>  	int setCrop(unsigned int pad, Rectangle *rect);
> >>>  	int setCompose(unsigned int pad, Rectangle *rect);
> >>>
> >>> +	int enumFormat(unsigned int pad, V4L2SubdeviceFormatEnum *formatEnum);
> >>>  	int getFormat(unsigned int pad, V4L2SubdeviceFormat *format);
> >>>  	int setFormat(unsigned int pad, V4L2SubdeviceFormat *format);
> >>>
> >>> diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> >>> index b436f73cc75f..5665154a2762 100644
> >>> --- a/src/libcamera/v4l2_subdevice.cpp
> >>> +++ b/src/libcamera/v4l2_subdevice.cpp
> >>> @@ -26,6 +26,52 @@ namespace libcamera {
> >>>
> >>>  LOG_DEFINE_CATEGORY(V4L2Subdev)
> >>>
> >>> +/**
> >>> + * \struct V4L2SubdeviceFormatEnum
> >>> + * \brief The V4L2 sub-device image size enumeration
> >>> + *
> >>> + * This structure describes an image resolution as enumerated by the V4L2
> >>> + * sub-device. The structure is used as format exchange between the caller and
> >>> + * the enumFormat() method. The caller is responsible to fill the media bus
> >>> + * code to use and the index of the format to be enumerated.
> >>> + */
> >>> +
> >>> +/**
> >>> + * \var V4L2SubdeviceFormatEnum::index
> >>> + * \brief The index of the format to be enumerated
> >>> + */
> >>> +
> >>> +/**
> >>> + * \var V4L2SubdeviceFormatEnum::mbus_code
> >>> + * \brief The pixel format identification code for the formats to enumerate
> >>> + *
> >>> + * \sa V4L2SubdeviceFormat for media bus format pixel code description.
> >>> + */
> >>> +
> >>> +/**
> >>> + * \var V4L2SubdeviceFormatEnum::minWidth
> >>> + * \brief The minimum width of the enumerated format as reported by the V4L2
> >>> + * sub-device
> >>> + */
> >>> +
> >>> +/**
> >>> + * \var V4L2SubdeviceFormatEnum::maxWidth
> >>> + * \brief The maximum width of the enumerated format as reported by the V4L2
> >>> + * sub-device
> >>> + */
> >>> +
> >>> +/**
> >>> + * \var V4L2SubdeviceFormatEnum::minHeight
> >>> + * \brief The minimum height of the enumerated format as reported by the V4L2
> >>> + * sub-device
> >>> + */
> >>> +
> >>> +/**
> >>> + * \var V4L2SubdeviceFormatEnum::maxHeight
> >>> + * \brief The maximum height of the enumerated format as reported by the V4L2
> >>> + * sub-device
> >>> + */
> >>> +
> >>>  /**
> >>>   * \struct V4L2SubdeviceFormat
> >>>   * \brief The V4L2 sub-device image format and sizes
> >>> @@ -171,6 +217,50 @@ int V4L2Subdevice::setCompose(unsigned int pad, Rectangle *rect)
> >>>  	return setSelection(pad, V4L2_SEL_TGT_COMPOSE, rect);
> >>>  }
> >>>
> >>> +/**
> >>> + * \brief Enumerate the sub-device image resolutions
> >>> + * \param[in] pad The 0-indexed pad number to enumerate formats on
> >>> + * \param[inout] formatEnum The format enumeration description
> >>> + *
> >>> + * The method retrieve the image resolution of the image format with index
> >>> + * formatEnum.index for the pixel format specified by formatEnum.mbus_code.
> >>> + *
> >>> + * To enumerate image resolutions, the caller shall start enumerating all
> >>> + * formats by setting the formatEnum.index field to 0, and increasing it by
> >>> + * one for any successive call, until the -EINVAL return code is returned.
> >>
> >> Should we not help pipeline handlers by hiding this? And instead return
> >> a vector of V4L2SubdeviceFormatEnum with all formats?
> >>
> >
> > Yes, you and Laurent had the same suggestion and is surely better.
> > I'll re-implement this.
> >
> >>> + *
> >>> + * \return 0 on success, or a negative error code otherwise
> >>> + */
> >>> +int V4L2Subdevice::enumFormat(unsigned int pad,
> >>> +			      V4L2SubdeviceFormatEnum *formatEnum)
> >>> +{
> >>> +	struct v4l2_subdev_frame_size_enum sizeEnum = {};
> >>> +
> >>> +	sizeEnum.index = formatEnum->index;
> >>> +	sizeEnum.code = formatEnum->mbus_code;
> >>> +	sizeEnum.pad = pad;
> >>
> >> This is confusing, index and code comes from formatEnum while pad is a
> >> separate argument.
> >>
> >
> > All V4L2Subdevice methods accepts a pad as first argument. I would
> > keep this consistent.
> >
> >>> +	sizeEnum.which = V4L2_SUBDEV_FORMAT_ACTIVE;
> >>
> >> I think this should be configurable by the caller or other way
> >> customisable. In the not so distant future we will need to add support
> >> for V4L2_SUBDEV_FORMAT_TRY in a lot of places better to prepare for it
> >> :-)
> >
> > I'm really not sure about this one, I could add a field to
> > V4L2SubdeviceFormatEnum for this...
> >
> 
> Re-thinking about this, I would leave this out until we don't define a
> way to handle FORMAT_TRY globally, as otherwise I would have to expose
> that flag outside of V4L2Subdevice which I would prefer not to...

I think you made the right decision.

> >>> +
> >>> +	int ret = ioctl(fd_, VIDIOC_SUBDEV_ENUM_FRAME_SIZE, &sizeEnum);
> >>> +	if (ret) {
> >>> +		ret = -errno;
> >>> +		if (ret == -EINVAL)
> >>> +			return ret;
> >>> +
> >>> +		LOG(V4L2Subdev, Error)
> >>> +			<< "Unable to enumerate format on pad " << pad
> >>> +			<< " of " << deviceNode_ << ": " << strerror(-ret);
> >>> +		return ret;
> >>> +	}
> >>> +
> >>> +	formatEnum->maxWidth = sizeEnum.max_width;
> >>> +	formatEnum->minWidth = sizeEnum.min_width;
> >>> +	formatEnum->maxHeight = sizeEnum.max_height;
> >>> +	formatEnum->minHeight = sizeEnum.min_height;
> >>> +
> >>> +	return 0;
> >>> +}
> >>> +
> >>>  /**
> >>>   * \brief Retrieve the image format set on one of the V4L2 subdevice pads
> >>>   * \param[in] pad The 0-indexed pad number the format is to be retrieved from

-- 
Regards,

Laurent Pinchart