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media: uapi: Add 3a stats buffer for mali-c55

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Describe the format of the 3A statistics buffers in the userspace API
header for the mali-c55 ISP.

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 2025-11-11 16:15:53 +00:00 committed by Hans Verkuil
parent 4d36f73236
commit c7f832f6f8
2 changed files with 171 additions and 0 deletions
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MAINTAINERS
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@ -2116,6 +2116,7 @@ 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: drivers/media/platform/arm/mali-c55/
F: include/uapi/linux/media/arm/mali-c55-config.h
ARM MALI PANTHOR DRM DRIVER
M: Boris Brezillon <boris.brezillon@collabora.com>

170
include/uapi/linux/media/arm/mali-c55-config.h
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@ -8,6 +8,7 @@
#ifndef __UAPI_MALI_C55_CONFIG_H
#define __UAPI_MALI_C55_CONFIG_H
#include <linux/types.h>
#include <linux/v4l2-controls.h>
#define V4L2_CID_MALI_C55_CAPABILITIES (V4L2_CID_USER_MALI_C55_BASE + 0x0)
@ -23,4 +24,173 @@
#define MALI_C55_GPS_FRSCALER (1U << 9)
#define MALI_C55_GPS_DS_PIPE (1U << 10)
/*
* Frames are split into zones of almost equal width and height - a zone is a
* rectangular tile of a frame. The metering blocks within the ISP collect
* aggregated statistics per zone. A maximum of 15x15 zones can be configured,
* and so the statistics buffer within the hardware is sized to accommodate
* that.
*
* The utilised number of zones is runtime configurable.
*/
#define MALI_C55_MAX_ZONES (15 * 15)
/**
* struct mali_c55_ae_1024bin_hist - Auto Exposure 1024-bin histogram statistics
*
* @bins: 1024 element array of 16-bit pixel counts.
*
* The 1024-bin histogram module collects image-global but zone-weighted
* intensity distributions of pixels in fixed-width bins. The modules can be
* configured into different "plane modes" which affect the contents of the
* collected statistics. In plane mode 0, pixel intensities are taken regardless
* of colour plane into a single 1024-bin histogram with a bin width of 4. In
* plane mode 1, four 256-bin histograms with a bin width of 16 are collected -
* one for each CFA colour plane. In plane modes 4, 5, 6 and 7 two 512-bin
* histograms with a bin width of 8 are collected - in each mode one of the
* colour planes is collected into the first histogram and all the others are
* combined into the second. The histograms are stored consecutively in the bins
* array.
*
* The 16-bit pixel counts are stored as a 4-bit exponent in the most
* significant bits followed by a 12-bit mantissa. Conversion to a usable
* format can be done according to the following pseudo-code::
*
* if (e == 0) {
* bin = m * 2;
* } else {
* bin = (m + 4096) * 2^e
* }
*
* where
* e is the exponent value in range 0..15
* m is the mantissa value in range 0..4095
*
* The pixels used in calculating the statistics can be masked using three
* methods:
*
* 1. Pixels can be skipped in X and Y directions independently.
* 2. Minimum/Maximum intensities can be configured
* 3. Zones can be differentially weighted, including 0 weighted to mask them
*
* The data for this histogram can be collected from different tap points in the
* ISP depending on configuration - after the white balance or digital gain
* blocks, or immediately after the input crossbar.
*/
struct mali_c55_ae_1024bin_hist {
__u16 bins[1024];
} __attribute__((packed));
/**
* struct mali_c55_ae_5bin_hist - Auto Exposure 5-bin histogram statistics
*
* @hist0: 16-bit normalised pixel count for the 0th intensity bin
* @hist1: 16-bit normalised pixel count for the 1st intensity bin
* @hist3: 16-bit normalised pixel count for the 3rd intensity bin
* @hist4: 16-bit normalised pixel count for the 4th intensity bin
*
* The ISP generates a 5-bin histogram of normalised pixel counts within bins of
* pixel intensity for each of 225 possible zones within a frame. The centre bin
* of the histogram for each zone is not available from the hardware and must be
* calculated by subtracting the values of hist0, hist1, hist3 and hist4 from
* 0xffff as in the following equation:
*
* hist2 = 0xffff - (hist0 + hist1 + hist3 + hist4)
*/
struct mali_c55_ae_5bin_hist {
__u16 hist0;
__u16 hist1;
__u16 hist3;
__u16 hist4;
} __attribute__((packed));
/**
* struct mali_c55_awb_average_ratios - Auto White Balance colour ratios
*
* @avg_rg_gr: Average R/G or G/R ratio in Q4.8 format.
* @avg_bg_br: Average B/G or B/R ratio in Q4.8 format.
* @num_pixels: The number of pixels used in the AWB calculation
*
* The ISP calculates and collects average colour ratios for each zone in an
* image and stores them in Q4.8 format (the lowest 8 bits are fractional, with
* bits [11:8] representing the integer). The exact ratios collected (either
* R/G, B/G or G/R, B/R) are configurable through the parameters buffer. The
* value of the 4 high bits is undefined.
*/
struct mali_c55_awb_average_ratios {
__u16 avg_rg_gr;
__u16 avg_bg_br;
__u32 num_pixels;
} __attribute__((packed));
/**
* struct mali_c55_af_statistics - Auto Focus edge and intensity statistics
*
* @intensity_stats: Packed mantissa and exponent value for pixel intensity
* @edge_stats: Packed mantissa and exponent values for edge intensity
*
* The ISP collects the squared sum of pixel intensities for each zone within a
* configurable Region of Interest on the frame. Additionally, the same data are
* collected after being passed through a bandpass filter which removes high and
* low frequency components - these are referred to as the edge statistics.
*
* The intensity and edge statistics for a zone can be used to calculate the
* contrast information for a zone
*
* C = E2 / I2
*
* Where I2 is the intensity statistic for a zone and E2 is the edge statistic
* for that zone. Optimum focus is reached when C is at its maximum.
*
* The intensity and edge statistics are stored packed into a non-standard 16
* bit floating point format, where the 7 most significant bits represent the
* exponent and the 9 least significant bits the mantissa. This format can be
* unpacked with the following pseudocode::
*
* if (e == 0) {
* x = m;
* } else {
* x = 2^e-1 * (m + 2^9)
* }
*
* where
* e is the exponent value in range 0..127
* m is the mantissa value in range 0..511
*/
struct mali_c55_af_statistics {
__u16 intensity_stats;
__u16 edge_stats;
} __attribute__((packed));
/**
* struct mali_c55_stats_buffer - 3A statistics for the mali-c55 ISP
*
* @ae_1024bin_hist: 1024-bin frame-global pixel intensity histogram
* @iridix_1024bin_hist: Post-Iridix block 1024-bin histogram
* @ae_5bin_hists: 5-bin pixel intensity histograms for AEC
* @reserved1: Undefined buffer space
* @awb_ratios: Color balance ratios for Auto White Balance
* @reserved2: Undefined buffer space
* @af_statistics: Pixel intensity statistics for Auto Focus
* @reserved3: Undefined buffer space
*
* This struct describes the metering statistics space in the Mali-C55 ISP's
* hardware in its entirety. The space between each defined area is marked as
* "unknown" and may not be 0, but should not be used. The @ae_5bin_hists,
* @awb_ratios and @af_statistics members are arrays of statistics per-zone.
* The zones are arranged in the array in raster order starting from the top
* left corner of the image.
*/
struct mali_c55_stats_buffer {
struct mali_c55_ae_1024bin_hist ae_1024bin_hist;
struct mali_c55_ae_1024bin_hist iridix_1024bin_hist;
struct mali_c55_ae_5bin_hist ae_5bin_hists[MALI_C55_MAX_ZONES];
__u32 reserved1[14];
struct mali_c55_awb_average_ratios awb_ratios[MALI_C55_MAX_ZONES];
__u32 reserved2[14];
struct mali_c55_af_statistics af_statistics[MALI_C55_MAX_ZONES];
__u32 reserved3[15];
} __attribute__((packed));
#endif /* __UAPI_MALI_C55_CONFIG_H */