[PATCH 2/2] media: arm: mali-c55: Add support for RGB Gamma
From: Jacopo Mondi
Date: Tue Jun 16 2026 - 09:05:35 EST
From: Jacopo Mondi <jacopo.mondi+renesas@xxxxxxxxxxxxxxxx>
Add support for Gamma curve correction for the Mali C55 ISP.
Define a new block in the uAPI using the extensible v4l2-isp format and
implement support for configuring the RGB Gamma parameters in the
mali-c55 parameters handler.
Signed-off-by: Jacopo Mondi <jacopo.mondi+renesas@xxxxxxxxxxxxxxxx>
---
.../media/platform/arm/mali-c55/mali-c55-params.c | 75 ++++++++++++++++++++++
.../platform/arm/mali-c55/mali-c55-registers.h | 5 ++
include/uapi/linux/media/arm/mali-c55-config.h | 46 ++++++++++++-
3 files changed, 125 insertions(+), 1 deletion(-)
diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-params.c b/drivers/media/platform/arm/mali-c55/mali-c55-params.c
index 96f1b28a6d77..913e8c7fef73 100644
--- a/drivers/media/platform/arm/mali-c55/mali-c55-params.c
+++ b/drivers/media/platform/arm/mali-c55/mali-c55-params.c
@@ -47,6 +47,8 @@
* @shading_config: For header->type == MALI_C55_PARAM_MESH_SHADING_CONFIG
* @shading_selection: For header->type == MALI_C55_PARAM_MESH_SHADING_SELECTION
* @ccm: For header->type == MALI_C55_PARAM_BLOCK_CCM
+ * @gamma: For header->type == MALI_C55_PARAM_BLOCK_GAMMA_FR and
+ * header->type = MALI_C55_PARAM_BLOCK_GAMMA_DS
* @data: Allows easy initialisation of a union variable with a
* pointer into a __u8 array.
*/
@@ -61,6 +63,7 @@ union mali_c55_params_block {
const struct mali_c55_params_mesh_shading_config *shading_config;
const struct mali_c55_params_mesh_shading_selection *shading_selection;
const struct mali_c55_params_ccm *ccm;
+ const struct mali_c55_params_gamma *gamma;
const __u8 *data;
};
@@ -462,6 +465,70 @@ static void mali_c55_params_ccm(struct mali_c55 *mali_c55,
mali_c55_ctx_write(mali_c55, MALI_C55_REG_CCM_ENABLE, 1);
}
+static void mali_c55_params_gamma(struct mali_c55 *mali_c55,
+ union mali_c55_params_block block,
+ __u32 offset, __u32 lut_base)
+{
+ const struct mali_c55_params_gamma *params = block.gamma;
+
+ if (block.header->flags & V4L2_ISP_PARAMS_FL_BLOCK_DISABLE) {
+ mali_c55_ctx_update_bits(mali_c55,
+ MALI_C55_REG_GAMMA_RGB_ENABLE + offset,
+ MALI_C55_GAMMA_ENABLE_MASK, 0x00);
+ return;
+ }
+
+ mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_GAMMA_GAINS_1 + offset,
+ MALI_C55_GAMMA_GAIN_R_MASK, params->gains[0]);
+ mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_GAMMA_GAINS_1 + offset,
+ MALI_C55_GAMMA_GAIN_G_MASK,
+ MALI_C55_GAMMA_GAIN_G(params->gains[1]));
+ mali_c55_ctx_update_bits(mali_c55, MALI_C55_REG_GAMMA_GAINS_2 + offset,
+ MALI_C55_GAMMA_GAIN_B_MASK, params->gains[2]);
+ mali_c55_ctx_update_bits(mali_c55,
+ MALI_C55_REG_GAMMA_OFFSETS_1 + offset,
+ MALI_C55_GAMMA_OFFSET_R_MASK,
+ params->offs[0]);
+ mali_c55_ctx_update_bits(mali_c55,
+ MALI_C55_REG_GAMMA_OFFSETS_1 + offset,
+ MALI_C55_GAMMA_OFFSET_G_MASK,
+ MALI_C55_GAMMA_OFFSET_G(params->offs[1]));
+ mali_c55_ctx_update_bits(mali_c55,
+ MALI_C55_REG_GAMMA_OFFSETS_2 + offset,
+ MALI_C55_GAMMA_OFFSET_B_MASK,
+ params->offs[2]);
+
+ for (unsigned int i = 0; i < MALI_C55_NUM_GAMMA_LUT_ELEMENTS; i++) {
+ __u32 addr = lut_base + (i * 4);
+ mali_c55_ctx_write(mali_c55, addr, params->lut[i]);
+ }
+
+ mali_c55_ctx_update_bits(mali_c55,
+ MALI_C55_REG_GAMMA_RGB_ENABLE + offset,
+ MALI_C55_GAMMA_ENABLE_MASK, 0x1);
+
+}
+
+static void mali_c55_params_gamma_fr(struct mali_c55 *mali_c55,
+ union mali_c55_params_block block)
+{
+ return mali_c55_params_gamma(mali_c55, block,
+ MALI_C55_CAP_DEV_FR_REG_OFFSET,
+ MALI_C55_REG_FR_GAMMA_RGB_MEM);
+}
+
+static void mali_c55_params_gamma_ds(struct mali_c55 *mali_c55,
+ union mali_c55_params_block block)
+{
+ /* We cannot apply parameters to DS if it is not fitted. */
+ if (!(mali_c55->capabilities & MALI_C55_GPS_DS_PIPE_FITTED))
+ return;
+
+ return mali_c55_params_gamma(mali_c55, block,
+ MALI_C55_CAP_DEV_DS_REG_OFFSET,
+ MALI_C55_REG_DS_GAMMA_RGB_MEM);
+}
+
static const mali_c55_params_handler mali_c55_params_handlers[] = {
[MALI_C55_PARAM_BLOCK_SENSOR_OFFS] = &mali_c55_params_sensor_offs,
[MALI_C55_PARAM_BLOCK_AEXP_HIST] = &mali_c55_params_aexp_hist,
@@ -475,6 +542,8 @@ static const mali_c55_params_handler mali_c55_params_handlers[] = {
[MALI_C55_PARAM_MESH_SHADING_CONFIG] = &mali_c55_params_lsc_config,
[MALI_C55_PARAM_MESH_SHADING_SELECTION] = &mali_c55_params_lsc_selection,
[MALI_C55_PARAM_BLOCK_CCM] = &mali_c55_params_ccm,
+ [MALI_C55_PARAM_BLOCK_GAMMA_FR] = &mali_c55_params_gamma_fr,
+ [MALI_C55_PARAM_BLOCK_GAMMA_DS] = &mali_c55_params_gamma_ds,
};
static const struct v4l2_isp_params_block_type_info
@@ -515,6 +584,12 @@ mali_c55_params_block_types_info[] = {
[MALI_C55_PARAM_BLOCK_CCM] = {
.size = sizeof(struct mali_c55_params_ccm),
},
+ [MALI_C55_PARAM_BLOCK_GAMMA_FR] = {
+ .size = sizeof(struct mali_c55_params_gamma),
+ },
+ [MALI_C55_PARAM_BLOCK_GAMMA_DS] = {
+ .size = sizeof(struct mali_c55_params_gamma),
+ },
};
static_assert(ARRAY_SIZE(mali_c55_params_handlers) ==
diff --git a/drivers/media/platform/arm/mali-c55/mali-c55-registers.h b/drivers/media/platform/arm/mali-c55/mali-c55-registers.h
index f098effde7b4..7a606bd2e843 100644
--- a/drivers/media/platform/arm/mali-c55/mali-c55-registers.h
+++ b/drivers/media/platform/arm/mali-c55/mali-c55-registers.h
@@ -425,11 +425,13 @@ enum mali_c55_interrupts {
#define MALI_C55_REG_GAMMA_GAINS_1 0x1c068
#define MALI_C55_GAMMA_GAIN_R_MASK GENMASK(11, 0)
#define MALI_C55_GAMMA_GAIN_G_MASK GENMASK(27, 16)
+#define MALI_C55_GAMMA_GAIN_G(x) ((x) << 16)
#define MALI_C55_REG_GAMMA_GAINS_2 0x1c06c
#define MALI_C55_GAMMA_GAIN_B_MASK GENMASK(11, 0)
#define MALI_C55_REG_GAMMA_OFFSETS_1 0x1c070
#define MALI_C55_GAMMA_OFFSET_R_MASK GENMASK(11, 0)
#define MALI_C55_GAMMA_OFFSET_G_MASK GENMASK(27, 16)
+#define MALI_C55_GAMMA_OFFSET_G(x) ((x) << 16)
#define MALI_C55_REG_GAMMA_OFFSETS_2 0x1c074
#define MALI_C55_GAMMA_OFFSET_B_MASK GENMASK(11, 0)
@@ -441,6 +443,9 @@ enum mali_c55_interrupts {
#define MALI_C55_REG_FR_GAMMA_RGB_ENABLE 0x1c064
#define MALI_C55_REG_DS_GAMMA_RGB_ENABLE 0x1c1d8
+#define MALI_C55_REG_FR_GAMMA_RGB_MEM 0x18280
+#define MALI_C55_REG_DS_GAMMA_RGB_MEM 0x18484
+
#define MALI_C55_REG_FR_SCALER_HFILT 0x34a8
#define MALI_C55_REG_FR_SCALER_VFILT 0x44a8
#define MALI_C55_REG_DS_SCALER_HFILT 0x14a8
diff --git a/include/uapi/linux/media/arm/mali-c55-config.h b/include/uapi/linux/media/arm/mali-c55-config.h
index 0b2085eed81b..06eb85a6d66a 100644
--- a/include/uapi/linux/media/arm/mali-c55-config.h
+++ b/include/uapi/linux/media/arm/mali-c55-config.h
@@ -36,6 +36,9 @@
*/
#define MALI_C55_MAX_ZONES (15 * 15)
+/* Number of RGB gamma LUT entries. */
+#define MALI_C55_NUM_GAMMA_LUT_ELEMENTS 129
+
/**
* struct mali_c55_ae_1024bin_hist - Auto Exposure 1024-bin histogram statistics
*
@@ -220,6 +223,8 @@ struct mali_c55_stats_buffer {
* @MALI_C55_PARAM_MESH_SHADING_CONFIG : Mesh shading tables configuration
* @MALI_C55_PARAM_MESH_SHADING_SELECTION: Mesh shading table selection
* @MALI_C55_PARAM_BLOCK_CCM: Colour correction matrix
+ * @MALI_C55_PARAM_BLOCK_GAMMA_FR: Gamma gain and offset for FR pipe
+ * @MALI_C55_PARAM_BLOCK_GAMMA_DS: Gamma gain and offset for DS pipe
*/
enum mali_c55_param_block_type {
MALI_C55_PARAM_BLOCK_SENSOR_OFFS,
@@ -234,6 +239,8 @@ enum mali_c55_param_block_type {
MALI_C55_PARAM_MESH_SHADING_CONFIG,
MALI_C55_PARAM_MESH_SHADING_SELECTION,
MALI_C55_PARAM_BLOCK_CCM,
+ MALI_C55_PARAM_BLOCK_GAMMA_FR,
+ MALI_C55_PARAM_BLOCK_GAMMA_DS,
};
/**
@@ -795,6 +802,41 @@ struct mali_c55_params_ccm {
__u16 offs[3];
};
+/**
+ * struct mali_c55_params_gamma - RGB Gamma correction
+ *
+ * Gamma correction is used to program a standard gamma curve such as the sRGB
+ * one. It provides gains and offsets to implement contrast adjustments.
+ *
+ * Gamma correction is applied on both the FR and DS pipes separately in the RGB
+ * colour domain where the following operations take place:
+ * 1) An offset is subtracted from each colour channel
+ * 2) Each colour channel is multiplied by a gain
+ * 3) The Gamma LUT is applied to each colour channel
+ *
+ * The Gamma LUT has 129 entries where each node is an unsigned 12 bit number.
+ * It is expected that LUT[0]=0 and LUT[128]=0xffff, with the other 127 values
+ * defining the Gamma correction curve.
+ *
+ * As one Gamma correction block is available on both the FR and DS pipes, the
+ * header.type field should be set to one of either
+ * MALI_C55_PARAM_BLOCK_GAMMA_FR or MALI_C55_PARAM_BLOCK_GAMMA_DS from
+ * :c:type:`mali_c55_param_block_type`.
+ *
+ * @header: The Mali-C55 parameters block header
+ * @gains: Gains for the red, green and blue channel in unsigned Q4.8 format
+ * @offs: Offsets subtracted from the red, green and blue channels
+ * in unsigned 12-bit format
+ * @lut: 129-node Gamma LUT in u0.12 format
+ */
+struct mali_c55_params_gamma {
+ struct v4l2_isp_params_block_header header;
+ __u8 rgb_enable;
+ __u16 gains[3];
+ __u16 offs[3];
+ __u32 lut[MALI_C55_NUM_GAMMA_LUT_ELEMENTS];
+};
+
/**
* define MALI_C55_PARAMS_MAX_SIZE - Maximum size of all Mali C55 Parameters
*
@@ -819,6 +861,8 @@ struct mali_c55_params_ccm {
sizeof(struct mali_c55_params_awb_gains) + \
sizeof(struct mali_c55_params_mesh_shading_config) + \
sizeof(struct mali_c55_params_mesh_shading_selection) + \
- sizeof(struct mali_c55_params_ccm))
+ sizeof(struct mali_c55_params_ccm) + \
+ sizeof(struct mali_c55_params_gamma) + \
+ sizeof(struct mali_c55_params_gamma))
#endif /* __UAPI_MALI_C55_CONFIG_H */
--
2.54.0