mirror of
https://github.com/torvalds/linux.git
synced 2025-12-07 20:06:24 +00:00
Documentation: media: mali-c55: Add Statistics documentation
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. Tested-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> Acked-by: Nayden Kanchev <nayden.kanchev@arm.com> Co-developed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> Signed-off-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> Signed-off-by: Daniel Scally <dan.scally@ideasonboard.com> Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>
This commit is contained in:
Daniel Scally
committed by
Hans Verkuil
Hans Verkuil
parent
5d1f7403d6
commit
b35d9f3e30
@@ -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
|
||||
@@ -333,6 +334,63 @@ 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_STATS <v4l2-meta-fmt-mali-c55-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/
|
||||
|
||||
@@ -13,6 +13,7 @@ These formats are used for the :ref:`metadata` interface only.
|
||||
.. toctree::
|
||||
:maxdepth: 1
|
||||
|
||||
metafmt-arm-mali-c55
|
||||
metafmt-c3-isp
|
||||
metafmt-d4xx
|
||||
metafmt-generic
|
||||
|
||||
@@ -0,0 +1,29 @@
|
||||
.. SPDX-License-Identifier: GPL-2.0
|
||||
|
||||
.. _v4l2-meta-fmt-mali-c55-stats:
|
||||
|
||||
*************************************
|
||||
V4L2_META_FMT_MALI_C55_STATS ('C55S')
|
||||
*************************************
|
||||
|
||||
3A Statistics
|
||||
=============
|
||||
|
||||
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
|
||||
@@ -2115,6 +2115,7 @@ F: Documentation/admin-guide/media/mali-c55-graph.dot
|
||||
F: Documentation/admin-guide/media/mali-c55.rst
|
||||
F: Documentation/devicetree/bindings/media/arm,mali-c55.yaml
|
||||
F: Documentation/userspace-api/media/drivers/mali-c55.rst
|
||||
F: Documentation/userspace-api/media/v4l/metafmt-arm-mali-c55.rst
|
||||
F: drivers/media/platform/arm/mali-c55/
|
||||
F: include/uapi/linux/media/arm/mali-c55-config.h
|
||||
|
||||
|
||||
Reference in New Issue
Block a user