Hi Dan, Thank you for the patch. On Wed, May 29, 2024 at 04:28:54PM +0100, Daniel Scally wrote: > Add documentation explaining the ability to capture statistics from > the mali-c55 driver's new V4L2 device, as well as the various tap > points from which those statistics can be drawn in the ISP's > processing flow. Additionally add a page detailing the new V4L2 > meta format for the mali-c55 statistics. > > Acked-by: Nayden Kanchev <nayden.kanchev@xxxxxxx> > Co-developed-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> > Signed-off-by: Jacopo Mondi <jacopo.mondi@xxxxxxxxxxxxxxxx> > Signed-off-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx> > --- > Changes in v5: > > - New patch > > Documentation/admin-guide/media/mali-c55.rst | 60 ++++++++++++++++++- > .../userspace-api/media/v4l/meta-formats.rst | 1 + > .../media/v4l/metafmt-arm-mali-c55.rst | 28 +++++++++ > 3 files changed, 88 insertions(+), 1 deletion(-) > create mode 100644 Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst > > diff --git a/Documentation/admin-guide/media/mali-c55.rst b/Documentation/admin-guide/media/mali-c55.rst > index cf4176cb1e44..b75437f6e96a 100644 > --- a/Documentation/admin-guide/media/mali-c55.rst > +++ b/Documentation/admin-guide/media/mali-c55.rst > @@ -67,10 +67,11 @@ The driver has 4 V4L2 subdevices: > - `mali_c55 resizer fr`: The Full-Resolution pipe resizer > - `mali_c55 resizer ds`: The Downscale pipe resizer > > -The driver has 2 V4L2 video devices: > +The driver has 3 V4L2 video devices: > > - `mali-c55 fr`: The full-resolution pipe's capture device > - `mali-c55 ds`: The downscale pipe's capture device > +- `mali-c55 3a stats`: The 3A statistics capture device > > Frame sequences are synchronised across to two capture devices, meaning if one > pipe is started later than the other the sequence numbers returned in its > @@ -326,6 +327,63 @@ configured, followed by formats in the appropriate places: > # Set format on the video device and stream > yavta -f RGB565 -s 1920x1080 -c10 /dev/video0 > > +.. _mali-c55-3a-stats: > + > +Capturing ISP Statistics > +======================== > + > +The ISP is capable of producing statistics for consumption by image processing > +algorithms running in userspace. These statistics can be captured by queueing > +buffers to the `mali-c55 3a stats` V4L2 Device whilst the ISP is streaming. Only > +the :ref:`V4L2_META_FMT_MALI_C55_3A_STATS <v4l2-meta-fmt-mali-c55-3a-stats>` > +format is supported, so no format-setting need be done: > + > +.. code-block:: none > + > + # We assume the media graph has been configured to support RGB565 capture > + # from the mali-c55 fr V4L2 Device, which is at /dev/video0. The statistics > + # V4L2 device is at /dev/video3 > + > + yavta -f RGB565 -s 1920x1080 -c32 /dev/video0 && \ > + yavta -c10 -F /dev/video3 > + > +The layout of the buffer is described by :c:type:`mali_c55_stats_buffer`, > +but broadly statistics are generated to support three image processing > +algorithms; AEXP (Auto-Exposure), AWB (Auto-White Balance) and AF (Auto-Focus). > +These stats can be drawn from various places in the Mali C55 ISP pipeline, known > +as "tap points". This high-level block diagram is intended to explain where in > +the processing flow the statistics can be drawn from:: > + > + +--> AEXP-2 +----> AEXP-1 +--> AF-0 > + | +----> AF-1 | > + | | | > + +---------+ | +--------------+ | +--------------+ | > + | Input +-+-->+ Digital Gain +---+-->+ Black Level +---+---+ > + +---------+ +--------------+ +--------------+ | > + +-----------------------------------------------------------------+ > + | > + | +--------------+ +---------+ +----------------+ > + +-->| Sinter Noise +-+ White +--+--->| Lens Shading +--+---------------+ > + | Reduction | | Balance | | | | | | > + +--------------+ +---------+ | +----------------+ | | > + +---> AEXP-0 (A) +--> AEXP-0 (B) | > + +--------------------------------------------------------------------------+ > + | > + | +----------------+ +--------------+ +----------------+ > + +-->| Tone mapping +-+--->| Demosaicing +->+ Purple Fringe +-+-----------+ > + | | | +--------------+ | Correction | | | > + +----------------+ +-> AEXP-IRIDIX +----------------+ +---> AWB-0 | > + +----------------------------------------------------------------------------+ > + | +-------------+ +-------------+ > + +------------------->| Colour +---+--->| Output | > + | Correction | | | Pipelines | > + +-------------+ | +-------------+ > + +--> AWB-1 > + > +At present all statistics are drawn from the 0th tap point for each algorithm; > +I.E. AEXP statistics from AEXP-0 (A), AWB statistics from AWB-0 and AF > +statistics from AF-0. In the future this will be configurable. > + > References > ========== > .. [1] https://git.linuxtv.org/v4l-utils.git/ > diff --git a/Documentation/userspace-api/media/v4l/meta-formats.rst b/Documentation/userspace-api/media/v4l/meta-formats.rst > index c23aac823d2c..73c05cc35321 100644 > --- a/Documentation/userspace-api/media/v4l/meta-formats.rst > +++ b/Documentation/userspace-api/media/v4l/meta-formats.rst > @@ -15,6 +15,7 @@ These formats are used for the :ref:`metadata` interface only. > metafmt-d4xx > metafmt-generic > metafmt-intel-ipu3 > + metafmt-arm-mali-c55 Alphabetical order please. > metafmt-rkisp1 > metafmt-uvc > metafmt-vivid > diff --git a/Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst b/Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst > new file mode 100644 > index 000000000000..219a5dd42d70 > --- /dev/null > +++ b/Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst > @@ -0,0 +1,28 @@ > +.. SPDX-License-Identifier: GPL-2.0 > + > +.. _v4l2-meta-fmt-mali-c55-3a-stats: > + > +**************************************** > +V4L2_META_FMT_MALI_C55_3A_STATS ('C55S') > +**************************************** > + > +3A Statistics > +============= Missing blank line. Reviewed-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx> > +The ISP device collects different statistics over an input bayer frame. Those > +statistics can be obtained by userspace from the > +:ref:`mali-c55 3a stats <mali-c55-3a-stats>` metadata capture video node, using > +the :c:type:`v4l2_meta_format` interface. The buffer contains a single instance > +of the C structure :c:type:`mali_c55_stats_buffer` defined in > +``mali-c55-config.h``, so the structure can be obtained from the buffer by: > + > +.. code-block:: C > + > + struct mali_c55_stats_buffer *stats = > + (struct mali_c55_stats_buffer *)buf; > + > +For details of the statistics see :c:type:`mali_c55_stats_buffer`. > + > +Arm Mali-C55 uAPI data types > +============================ > + > +.. kernel-doc:: include/uapi/linux/media/arm/mali-c55-config.h -- Regards, Laurent Pinchart
