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

[Jacopo Mondi]

Hi Niklas,

On Thu, Feb 21, 2019 at 04:31:56PM +0100, Niklas Söderlund wrote:
> Hi Jacopo,
>
> Thanks for your patch.
>
> 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...

>
> > +
> > +	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
> > --
> > 2.20.1
> >
> > _______________________________________________
> > libcamera-devel mailing list
> > libcamera-devel at lists.libcamera.org
> > https://lists.libcamera.org/listinfo/libcamera-devel
>
> --
> Regards,
> Niklas Söderlund
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