Re: [PATCH v1] media: rkisp1: Add support for CAC

Jacopo Mondi
2026-03-25T15:21:19Z

Hi Barnabás

On Mon, Mar 23, 2026 at 03:02:16PM +0100, Barnabás Pőcze wrote:
> The CAC block implements chromatic aberration correction. Expose it to
> userspace using the extensible parameters format. This was tested on the
> i.MX8MP platform, but based on available documentation it is also present
> in the RK3399 variant (V10). Thus presumably also in later versions,
> so no feature flag is introduced.
>
> Signed-off-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>

Only minors..

> ---
> .../platform/rockchip/rkisp1/rkisp1-params.c | 69 ++++++++++++
> .../platform/rockchip/rkisp1/rkisp1-regs.h | 21 +++-
> include/uapi/linux/rkisp1-config.h | 106 +++++++++++++++++-
> 3 files changed, 193 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> index 6442436a5e428..b889af9dcee45 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-params.c
> @@ -64,6 +64,7 @@ union rkisp1_ext_params_config {
> struct rkisp1_ext_params_compand_bls_config compand_bls;
> struct rkisp1_ext_params_compand_curve_config compand_curve;
> struct rkisp1_ext_params_wdr_config wdr;
> + struct rkisp1_ext_params_cac_config cac;
> };
>
> enum rkisp1_params_formats {
> @@ -1413,6 +1414,48 @@ static void rkisp1_wdr_config(struct rkisp1_params *params,
> RKISP1_CIF_ISP_WDR_TONE_CURVE_YM_MASK);
> }
>
> +static void
> +rkisp1_cac_config(struct rkisp1_params *params,
> + const struct rkisp1_cif_isp_cac_config *arg)

Fits in one line without going over 80 cols

> +{
> + u32 regval;
> +
> + /*
> + * The enable bit is in the same register (RKISP1_CIF_ISP_CAC_CTRL),
> + * so only set the clipping mode, and do not modify the other bits.
> + */
> + regval = rkisp1_read(params->rkisp1, RKISP1_CIF_ISP_CAC_CTRL);
> + regval &= ~(RKISP1_CIF_ISP_CAC_CTRL_H_CLIP_MODE |
> + RKISP1_CIF_ISP_CAC_CTRL_V_CLIP_MODE);
> + regval |= FIELD_PREP(RKISP1_CIF_ISP_CAC_CTRL_H_CLIP_MODE, arg->h_clip_mode) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_CTRL_V_CLIP_MODE, arg->v_clip_mode);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_CTRL, regval);
> +
> + regval = FIELD_PREP(RKISP1_CIF_ISP_CAC_COUNT_START_H_MASK, arg->h_count_start) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_COUNT_START_V_MASK, arg->v_count_start);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_COUNT_START, regval);
> +
> + regval = FIELD_PREP(RKISP1_CIF_ISP_CAC_A_RED_MASK, arg->red[0]) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_A_BLUE_MASK, arg->blue[0]);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_A, regval);
> +
> + regval = FIELD_PREP(RKISP1_CIF_ISP_CAC_B_RED_MASK, arg->red[1]) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_B_BLUE_MASK, arg->blue[1]);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_B, regval);
> +
> + regval = FIELD_PREP(RKISP1_CIF_ISP_CAC_C_RED_MASK, arg->red[2]) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_C_BLUE_MASK, arg->blue[2]);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_C, regval);
> +
> + regval = FIELD_PREP(RKISP1_CIF_ISP_CAC_X_NORM_NF_MASK, arg->x_nf) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_X_NORM_NS_MASK, arg->x_ns);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_X_NORM, regval);
> +
> + regval = FIELD_PREP(RKISP1_CIF_ISP_CAC_Y_NORM_NF_MASK, arg->y_nf) |
> + FIELD_PREP(RKISP1_CIF_ISP_CAC_Y_NORM_NS_MASK, arg->y_ns);
> + rkisp1_write(params->rkisp1, RKISP1_CIF_ISP_CAC_Y_NORM, regval);
> +}
> +
> static void
> rkisp1_isp_isr_other_config(struct rkisp1_params *params,
> const struct rkisp1_params_cfg *new_params)
> @@ -2089,6 +2132,25 @@ static void rkisp1_ext_params_wdr(struct rkisp1_params *params,
> RKISP1_CIF_ISP_WDR_CTRL_ENABLE);
> }
>
> +static void rkisp1_ext_params_cac(struct rkisp1_params *params,
> + const union rkisp1_ext_params_config *block)
> +{
> + const struct rkisp1_ext_params_cac_config *cac = &block->cac;
> +
> + if (cac->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_DISABLE) {
> + rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_CAC_CTRL,
> + RKISP1_CIF_ISP_CAC_CTRL_ENABLE);
> + return;
> + }
> +
> + rkisp1_cac_config(params, &cac->config);
> +
> + if ((cac->header.flags & RKISP1_EXT_PARAMS_FL_BLOCK_ENABLE) &&
> + !(params->enabled_blocks & BIT(cac->header.type)))
> + rkisp1_param_set_bits(params, RKISP1_CIF_ISP_CAC_CTRL,
> + RKISP1_CIF_ISP_CAC_CTRL_ENABLE);
> +}
> +
> typedef void (*rkisp1_block_handler)(struct rkisp1_params *params,
> const union rkisp1_ext_params_config *config);
>
> @@ -2185,6 +2247,10 @@ static const struct rkisp1_ext_params_handler {
> .handler = rkisp1_ext_params_wdr,
> .group = RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> },
> + [RKISP1_EXT_PARAMS_BLOCK_TYPE_CAC] = {
> + .handler = rkisp1_ext_params_cac,
> + .group = RKISP1_EXT_PARAMS_BLOCK_GROUP_OTHERS,
> + },
> };
>
> #define RKISP1_PARAMS_BLOCK_INFO(block, data) \
> @@ -2215,6 +2281,7 @@ rkisp1_ext_params_block_types_info[] = {
> RKISP1_PARAMS_BLOCK_INFO(COMPAND_EXPAND, compand_curve),
> RKISP1_PARAMS_BLOCK_INFO(COMPAND_COMPRESS, compand_curve),
> RKISP1_PARAMS_BLOCK_INFO(WDR, wdr),
> + RKISP1_PARAMS_BLOCK_INFO(CAC, cac),
> };
>
> static_assert(ARRAY_SIZE(rkisp1_ext_params_handlers) ==
> @@ -2474,6 +2541,8 @@ void rkisp1_params_disable(struct rkisp1_params *params)
> rkisp1_ie_enable(params, false);
> rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_DPF_MODE,
> RKISP1_CIF_ISP_DPF_MODE_EN);
> + rkisp1_param_clear_bits(params, RKISP1_CIF_ISP_CAC_CTRL,
> + RKISP1_CIF_ISP_CAC_CTRL_ENABLE);
> }
>
> static const struct rkisp1_params_ops rkisp1_v10_params_ops = {
> diff --git a/drivers/media/platform/rockchip/rkisp1/rkisp1-regs.h b/drivers/media/platform/rockchip/rkisp1/rkisp1-regs.h
> index fbeb186cde0d5..8e25537459bbd 100644
> --- a/drivers/media/platform/rockchip/rkisp1/rkisp1-regs.h
> +++ b/drivers/media/platform/rockchip/rkisp1/rkisp1-regs.h
> @@ -724,6 +724,23 @@
> #define RKISP1_CIF_ISP_WDR_DMIN_STRENGTH_MASK GENMASK(20, 16)
> #define RKISP1_CIF_ISP_WDR_DMIN_STRENGTH_MAX 16U
>
> +/* CAC */
> +#define RKISP1_CIF_ISP_CAC_CTRL_ENABLE BIT(0)
> +#define RKISP1_CIF_ISP_CAC_CTRL_V_CLIP_MODE GENMASK(2, 1)
> +#define RKISP1_CIF_ISP_CAC_CTRL_H_CLIP_MODE GENMASK(3, 3)
> +#define RKISP1_CIF_ISP_CAC_COUNT_START_H_MASK GENMASK(12, 0)
> +#define RKISP1_CIF_ISP_CAC_COUNT_START_V_MASK GENMASK(28, 16)
> +#define RKISP1_CIF_ISP_CAC_A_RED_MASK GENMASK(8, 0)
> +#define RKISP1_CIF_ISP_CAC_A_BLUE_MASK GENMASK(24, 16)
> +#define RKISP1_CIF_ISP_CAC_B_RED_MASK GENMASK(8, 0)
> +#define RKISP1_CIF_ISP_CAC_B_BLUE_MASK GENMASK(24, 16)
> +#define RKISP1_CIF_ISP_CAC_C_RED_MASK GENMASK(8, 0)
> +#define RKISP1_CIF_ISP_CAC_C_BLUE_MASK GENMASK(24, 16)

All these masks for coefficients 0, 1 and 2 are identical. Maybe
#define RKISP1_CIF_ISP_CAC_RED_MASK GENMASK(8, 0)
#define RKISP1_CIF_ISP_CAC_BLUE_MASK GENMASK(24, 16)

is enough

> +#define RKISP1_CIF_ISP_CAC_X_NORM_NF_MASK GENMASK(4, 0)
> +#define RKISP1_CIF_ISP_CAC_X_NORM_NS_MASK GENMASK(19, 16)
> +#define RKISP1_CIF_ISP_CAC_Y_NORM_NF_MASK GENMASK(4, 0)
> +#define RKISP1_CIF_ISP_CAC_Y_NORM_NS_MASK GENMASK(19, 16)
> +
> /* =================================================================== */
> /* CIF Registers */
> /* =================================================================== */
> @@ -1196,8 +1213,8 @@
> #define RKISP1_CIF_ISP_CAC_A (RKISP1_CIF_ISP_CAC_BASE + 0x00000008)
> #define RKISP1_CIF_ISP_CAC_B (RKISP1_CIF_ISP_CAC_BASE + 0x0000000c)
> #define RKISP1_CIF_ISP_CAC_C (RKISP1_CIF_ISP_CAC_BASE + 0x00000010)
> -#define RKISP1_CIF_ISP_X_NORM (RKISP1_CIF_ISP_CAC_BASE + 0x00000014)
> -#define RKISP1_CIF_ISP_Y_NORM (RKISP1_CIF_ISP_CAC_BASE + 0x00000018)
> +#define RKISP1_CIF_ISP_CAC_X_NORM (RKISP1_CIF_ISP_CAC_BASE + 0x00000014)
> +#define RKISP1_CIF_ISP_CAC_Y_NORM (RKISP1_CIF_ISP_CAC_BASE + 0x00000018)
>
> #define RKISP1_CIF_ISP_EXP_BASE 0x00002600
> #define RKISP1_CIF_ISP_EXP_CTRL (RKISP1_CIF_ISP_EXP_BASE + 0x00000000)
> diff --git a/include/uapi/linux/rkisp1-config.h b/include/uapi/linux/rkisp1-config.h
> index b2d2a71f7baff..d8acccaddd0e9 100644
> --- a/include/uapi/linux/rkisp1-config.h
> +++ b/include/uapi/linux/rkisp1-config.h
> @@ -967,6 +967,92 @@ struct rkisp1_cif_isp_wdr_config {
> __u8 use_iref;
> };
>
> +/*
> + * enum rkisp1_cif_isp_cac_h_clip_mode - horizontal clipping mode
> + *
> + * @RKISP1_CIF_ISP_CAC_H_CLIP_MODE_4PX: +/- 4 pixels
> + * @RKISP1_CIF_ISP_CAC_H_CLIP_MODE_4_5PX: +/- 4/5 pixels depending on bayer position
> + */
> +enum rkisp1_cif_isp_cac_h_clip_mode {
> + RKISP1_CIF_ISP_CAC_H_CLIP_MODE_4PX = 0,
> + RKISP1_CIF_ISP_CAC_H_CLIP_MODE_4_5PX = 1,
> +};
> +
> +/**
> + * enum rkisp1_cif_isp_cac_v_clip_mode - vertical clipping mode
> + *
> + * @RKISP1_CIF_ISP_CAC_V_CLIP_MODE_2PX: +/- 2 pixels
> + * @RKISP1_CIF_ISP_CAC_V_CLIP_MODE_3PX: +/- 3 pixels
> + * @RKISP1_CIF_ISP_CAC_V_CLIP_MODE_3_4PX: +/- 3/4 pixels depending on bayer position
> + */
> +enum rkisp1_cif_isp_cac_v_clip_mode {
> + RKISP1_CIF_ISP_CAC_V_CLIP_MODE_2PX = 0,
> + RKISP1_CIF_ISP_CAC_V_CLIP_MODE_3PX = 1,
> + RKISP1_CIF_ISP_CAC_V_CLIP_MODE_3_4PX = 2,
> +};
> +
> +/**
> + * struct rkisp1_cif_isp_cac_config - chromatic aberration correction configuration
> + *
> + * The correction is carried out by shifting the red and blue pixels relative
> + * to the green ones, depending on the distance from the optical center:

Yes, the distance to the center is one parameter, but the shifting
amount depends on other things. I would drop the last part of the
sentence and move the description of the two below fields after the
text

> + *
> + * @h_count_start: horizontal coordinate of the optical center (13-bit unsigned integer; [1,8191])
> + * @v_count_start: vertical coordinate of the optical center (13-bit unsigned integer; [1,8191])

so these could go just before @x_nf

> + *
> + * For each pixel, the x/y distances from the optical center are calculated and

I forgot: did we establish that the correction is applied to the
euclidean distance or to x and y separately ?

> + * then transformed into the [0,255] range based on the following formula:

s/transformed/normalized ?

> + *
> + * (((d << 4) >> s) * f) >> 5
> + *
> + * where `d` is the distance, `s` and `f` are the normalization parameters:

Can you use 'ns' and 'nf' to match the below ?

> + *
> + * @x_nf: horizontal normalization scale parameter (5-bit unsigned integer; [0,31])
> + * @x_ns: horizontal normalization shift parameter (4-bit unsigned integer; [0,15])
> + *
> + * @y_nf: vertical normalization scale parameter (5-bit unsigned integer; [0,31])
> + * @y_ns: vertical normalization shift parameter (4-bit unsigned integer; [0,15])
> + *
> + * These parameters should be chosen based on the image resolution, the position
> + * of the optical center, and the shape of pixels: so that no normalized distance

s/pixels:/pixels/

> + * is larger than 255. If the pixels have square shape, the two sets of parameters
> + * should be equal.
> + *
> + * The actual amount of correction is calculated with a third degree polynomial:
> + *
> + * c[0] * r + c[1] * r^2 + c[2] * r^3
> + *
> + * where `c` is the set of coefficients for the given color, and `r` is distance:
> + *
> + * @red: red coefficients (5.4 two's complement; [-16,15.9375])
> + * @blue: blue coefficients (5.4 two's complement; [-16,15.9375])
> + *
> + * Finally, the amount is clipped as requested:
> + *
> + * @h_clip_mode: maximum horizontal shift (from enum rkisp1_cif_isp_cac_h_clip_mode)
> + * @v_clip_mode: maximum vertical shift (from enum rkisp1_cif_isp_cac_v_clip_mode)
> + *
> + * A positive result will shift away from the optical center, while a negative
> + * one will shift towards the optical center. In the latter case, the pixel
> + * values at the edges are duplicated.
> + */
> +struct rkisp1_cif_isp_cac_config {
> + __u8 h_clip_mode;
> + __u8 v_clip_mode;
> +
> + __u16 h_count_start;
> + __u16 v_count_start;
> +
> + __u16 red[3];
> + __u16 blue[3];
> +
> + __u8 x_nf;
> + __u8 x_ns;
> +
> + __u8 y_nf;
> + __u8 y_ns;
> +};
> +
> /*---------- PART2: Measurement Statistics ------------*/
>
> /**
> @@ -1161,6 +1247,7 @@ enum rkisp1_ext_params_block_type {
> RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_EXPAND,
> RKISP1_EXT_PARAMS_BLOCK_TYPE_COMPAND_COMPRESS,
> RKISP1_EXT_PARAMS_BLOCK_TYPE_WDR,
> + RKISP1_EXT_PARAMS_BLOCK_TYPE_CAC,
> };
>
> /* For backward compatibility */
> @@ -1507,6 +1594,22 @@ struct rkisp1_ext_params_wdr_config {
> struct rkisp1_cif_isp_wdr_config config;
> } __attribute__((aligned(8)));
>
> +/**
> + * struct rkisp1_ext_params_cac_config - RkISP1 extensible params CAC config
> + *
> + * RkISP1 extensible parameters CAC block.
> + * Identified by :c:type:`RKISP1_EXT_PARAMS_BLOCK_TYPE_CAC`.
> + *
> + * @header: The RkISP1 extensible parameters header, see
> + * :c:type:`rkisp1_ext_params_block_header`
> + * @config: CAC configuration, see
> + * :c:type:`rkisp1_cif_isp_cac_config`
> + */
> +struct rkisp1_ext_params_cac_config {
> + struct rkisp1_ext_params_block_header header;
> + struct rkisp1_cif_isp_cac_config config;
> +} __attribute__((aligned(8)));
> +
> /*
> * The rkisp1_ext_params_compand_curve_config structure is counted twice as it
> * is used for both the COMPAND_EXPAND and COMPAND_COMPRESS block types.
> @@ -1532,7 +1635,8 @@ struct rkisp1_ext_params_wdr_config {
> sizeof(struct rkisp1_ext_params_compand_bls_config) +\
> sizeof(struct rkisp1_ext_params_compand_curve_config) +\
> sizeof(struct rkisp1_ext_params_compand_curve_config) +\
> - sizeof(struct rkisp1_ext_params_wdr_config))
> + sizeof(struct rkisp1_ext_params_wdr_config) +\
> + sizeof(struct rkisp1_ext_params_cac_config))

All minors, please add
Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com>

Thanks
j

>
> /**
> * enum rksip1_ext_param_buffer_version - RkISP1 extensible parameters version
> --
> 2.53.0
>
>