[libcamera-devel] [PATCH v3 08/13] libcamera: v4l2_subdevice: Add format information

Mon Apr 27 14:54:06 CEST 2020

Hi Laurent,

On Sat, Apr 25, 2020 at 11:29:03PM +0300, Laurent Pinchart wrote:
> Hi Jacopo,
>
> Thank you for the patch.
>
> On Fri, Apr 24, 2020 at 11:52:59PM +0200, Jacopo Mondi wrote:
> > Define a map of static information associated with a media bus code.
> > Start by reporting the bits-per-pixel for each media bus code defined by
> > the V4L2 kernel API, to later expand it when necessary.
> >
> > Add to the V4L2SubdeviceFormat class a method to return the bits per
> > pixel, retrieved by inspecting the static map of format information.
> >
> > Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
> > ---
> >  src/libcamera/include/v4l2_subdevice.h |   3 +
> >  src/libcamera/v4l2_subdevice.cpp       | 113 +++++++++++++++++++++++++
> >  2 files changed, 116 insertions(+)
> >
> > diff --git a/src/libcamera/include/v4l2_subdevice.h b/src/libcamera/include/v4l2_subdevice.h
> > index 763ffadb61fb..43953a0a5a6c 100644
> > --- a/src/libcamera/include/v4l2_subdevice.h
> > +++ b/src/libcamera/include/v4l2_subdevice.h
> > @@ -23,10 +23,13 @@ namespace libcamera {
> >  class MediaDevice;
> >
> >  struct V4L2SubdeviceFormat {
> > +	using infoMap = std::map<uint32_t, uint8_t>;
>
> There's no need to define a type here as it's not used in the API, you
> can use it directly below.
>

I like to shorten the type though, and it does not actually brings
much obfuscation

> > +
> >  	uint32_t mbus_code;
> >  	Size size;
> >
> >  	const std::string toString() const;
> > +	uint8_t bitsPerPixel() const;
> >  };
> >
> >  class V4L2Subdevice : public V4L2Device
> > diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
> > index 4dcf8ce48754..6f72c363fc7f 100644
> > --- a/src/libcamera/v4l2_subdevice.cpp
> > +++ b/src/libcamera/v4l2_subdevice.cpp
> > @@ -14,6 +14,7 @@
> >  #include <sys/ioctl.h>
> >  #include <unistd.h>
> >
> > +#include <linux/media-bus-format.h>
> >  #include <linux/v4l2-subdev.h>
> >
> >  #include <libcamera/geometry.h>
> > @@ -32,6 +33,92 @@ namespace libcamera {
> >
> >  LOG_DECLARE_CATEGORY(V4L2)
> >
> > +namespace {
> > +
> > +/*
> > + * \var formatInfoMap
> > + * \brief A map that associates information to V4L2 media bus codes
> > + */
>
> No need for doxygen doc (that would require /** instead of /*) as it's
> purely internal.

This is intended. In other places for documentation not parsed by
doxygen we decided to maintain the doxygen style for consistency if
I'm not mistaken

>
> > +const V4L2SubdeviceFormat::infoMap formatInfoMap = {
>
> So here we would have
>
> const std::map<uint32_t, uint8_t> formatInfoMap = {
>

meh. I can drop it, but we used type shortcuts in other places.

> > +	{ V4L2_MBUS_FMT_RGB444_2X8_PADHI_BE, 16 },
> > +	{ V4L2_MBUS_FMT_RGB444_2X8_PADHI_LE, 16 },
> > +	{ V4L2_MBUS_FMT_RGB555_2X8_PADHI_BE, 16 },
> > +	{ V4L2_MBUS_FMT_RGB555_2X8_PADHI_LE, 16 },
> > +	{ V4L2_MBUS_FMT_BGR565_2X8_BE, 16 },
> > +	{ V4L2_MBUS_FMT_BGR565_2X8_LE, 16 },
> > +	{ V4L2_MBUS_FMT_RGB565_2X8_BE, 16 },
> > +	{ V4L2_MBUS_FMT_RGB565_2X8_LE, 16 },
> > +	{ V4L2_MBUS_FMT_RGB666_1X18, 18 },
> > +	{ V4L2_MBUS_FMT_RGB888_1X24, 24 },
> > +	{ V4L2_MBUS_FMT_RGB888_2X12_BE, 24 },
> > +	{ V4L2_MBUS_FMT_RGB888_2X12_LE, 24 },
> > +	{ V4L2_MBUS_FMT_ARGB8888_1X32, 32 },
> > +	{ V4L2_MBUS_FMT_Y8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_UV8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_UYVY8_1_5X8, 40 },
> > +	{ V4L2_MBUS_FMT_VYUY8_1_5X8, 40 },
> > +	{ V4L2_MBUS_FMT_YUYV8_1_5X8, 40 },
> > +	{ V4L2_MBUS_FMT_YVYU8_1_5X8, 40 },
> > +	{ V4L2_MBUS_FMT_UYVY8_2X8, 16 },
> > +	{ V4L2_MBUS_FMT_VYUY8_2X8, 16 },
> > +	{ V4L2_MBUS_FMT_YUYV8_2X8, 16 },
> > +	{ V4L2_MBUS_FMT_YVYU8_2X8, 16 },
> > +	{ V4L2_MBUS_FMT_Y10_1X10, 10 },
> > +	{ V4L2_MBUS_FMT_UYVY10_2X10, 20 },
> > +	{ V4L2_MBUS_FMT_VYUY10_2X10, 20 },
> > +	{ V4L2_MBUS_FMT_YUYV10_2X10, 20 },
> > +	{ V4L2_MBUS_FMT_YVYU10_2X10, 20 },
> > +	{ V4L2_MBUS_FMT_Y12_1X12, 12 },
> > +	{ V4L2_MBUS_FMT_UYVY8_1X16, 16 },
> > +	{ V4L2_MBUS_FMT_VYUY8_1X16, 16 },
> > +	{ V4L2_MBUS_FMT_YUYV8_1X16, 16 },
> > +	{ V4L2_MBUS_FMT_YVYU8_1X16, 16 },
> > +	{ V4L2_MBUS_FMT_YDYUYDYV8_1X16, 16 },
> > +	{ V4L2_MBUS_FMT_UYVY10_1X20, 20 },
> > +	{ V4L2_MBUS_FMT_VYUY10_1X20, 20 },
> > +	{ V4L2_MBUS_FMT_YUYV10_1X20, 20 },
> > +	{ V4L2_MBUS_FMT_YVYU10_1X20, 20 },
> > +	{ V4L2_MBUS_FMT_YUV10_1X30, 30 },
> > +	{ V4L2_MBUS_FMT_AYUV8_1X32, 32 },
> > +	{ V4L2_MBUS_FMT_UYVY12_2X12, 24 },
> > +	{ V4L2_MBUS_FMT_VYUY12_2X12, 24 },
> > +	{ V4L2_MBUS_FMT_YUYV12_2X12, 24 },
> > +	{ V4L2_MBUS_FMT_YVYU12_2X12, 24 },
> > +	{ V4L2_MBUS_FMT_UYVY12_1X24, 24 },
> > +	{ V4L2_MBUS_FMT_VYUY12_1X24, 24 },
> > +	{ V4L2_MBUS_FMT_YUYV12_1X24, 24 },
> > +	{ V4L2_MBUS_FMT_YVYU12_1X24, 24 },
> > +	{ V4L2_MBUS_FMT_SBGGR8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SGBRG8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SGRBG8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SRGGB8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_ALAW8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SGBRG10_ALAW8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SGRBG10_ALAW8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SRGGB10_ALAW8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_DPCM8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SGBRG10_DPCM8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SGRBG10_DPCM8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SRGGB10_DPCM8_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_2X8_PADHI_BE, 16 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_2X8_PADHI_LE, 16 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_2X8_PADLO_BE, 16 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_2X8_PADLO_LE, 16 },
> > +	{ V4L2_MBUS_FMT_SBGGR10_1X10, 10 },
> > +	{ V4L2_MBUS_FMT_SGBRG10_1X10, 10 },
> > +	{ V4L2_MBUS_FMT_SGRBG10_1X10, 10 },
> > +	{ V4L2_MBUS_FMT_SRGGB10_1X10, 10 },
> > +	{ V4L2_MBUS_FMT_SBGGR12_1X12, 24 },
> > +	{ V4L2_MBUS_FMT_SGBRG12_1X12, 24 },
> > +	{ V4L2_MBUS_FMT_SGRBG12_1X12, 24 },
> > +	{ V4L2_MBUS_FMT_SRGGB12_1X12, 24 },
> > +	{ V4L2_MBUS_FMT_JPEG_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_S5C_UYVY_JPEG_1X8, 8 },
> > +	{ V4L2_MBUS_FMT_AHSV8888_1X32, 32 },
> > +};
> > +
> > +}; /* namespace */
> > +
> >  /**
> >   * \struct V4L2SubdeviceFormat
> >   * \brief The V4L2 sub-device image format and sizes
> > @@ -60,6 +147,14 @@ LOG_DECLARE_CATEGORY(V4L2)
> >   * Section 4.15.3.1 of the above mentioned Linux kernel documentation section.
> >   */
> >
> > +/**
> > + * \typedef V4L2SubdeviceFormat::infoMap
> > + * \brief Map of static information associated with a V4L2 subdevice format
> > + *
> > + * \todo Expand with additional information. At the moment only the
> > + * bits-per-pixel information is reported.
> > + */
> > +
>
> And you can drop this too as the type doesn't need to be documented.
> What we may document later is a format info structure that would contain
> more than just the bpp, but there's no need to introduce that yet.
>

Does it hurt ?

> >  /**
> >   * \var V4L2SubdeviceFormat::mbus_code
> >   * \brief The image format bus code
> > @@ -81,6 +176,24 @@ const std::string V4L2SubdeviceFormat::toString() const
> >  	return ss.str();
> >  }
> >
> > +/**
> > + * \brief Retrieve the number of bits per pixel for the V4L2 subdevice format
> > + * \return The number of bits per pixel for the format, or default it to 8 if
> > + * the format's mbus code is not supported
>
> s/mbus/media bus/
>
> > + */
> > +uint8_t V4L2SubdeviceFormat::bitsPerPixel() const
> > +{
> > +	const auto it = formatInfoMap.find(mbus_code);
> > +	if (it == formatInfoMap.end()) {
> > +		LOG(V4L2, Error) << "No information available for format: '"
>
> s/://
>
> > +				 << toString() << "'";
> > +		/* Return 8 to avoid divisions by 0. */
> > +		return 8;
>
> I think we should return 0 and check for this condition in the caller.
> When we'll switch to a structure that will contain information about
> formats, the formatInfo() function will return a pointer, which will be
> null when the format is not known. I would prefer preparing the callers
> for this already.

Ack

Thanks
   j

>
> With these small changes,
>
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
>
> > +	}
> > +
> > +	return it->second;
> > +}
> > +
> >  /**
> >   * \class V4L2Subdevice
> >   * \brief A V4L2 subdevice as exposed by the Linux kernel
>
> --
> Regards,
>
> Laurent Pinchart