Re: [v8 14/14] media: rppx1: lin: Add support for gamma sensor linearization
From: Niklas Söderlund
Date: Sat May 16 2026 - 16:57:00 EST
Hello Jacopo,
Thanks for your self-review ;-)
On 2026-05-06 17:57:49 +0200, Jacopo Mondi wrote:
> Hi Niklas,
>
> On Mon, May 04, 2026 at 03:05:56AM +0200, Niklas Söderlund wrote:
> > From: Jai Luthra <jai.luthra@xxxxxxxxxxxxxxxx>
> >
> > Extend the RPPX1 driver to allow setting the gamma sensor linearization
> > configuration parameters. It uses the RPPX1 framework for parameters and
> > its writer abstraction to allow the user to control how, and when,
> > configuration is applied to the RPPX1.
> >
> > Signed-off-by: Jai Luthra <jai.luthra@xxxxxxxxxxxxxxxx>
> > Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@xxxxxxxxxxxx>
> > ---
> > .../platform/dreamchip/rppx1/rpp_module.h | 1 +
> > .../platform/dreamchip/rppx1/rpp_params.c | 5 ++
> > .../platform/dreamchip/rppx1/rppx1_lin.c | 55 +++++++++++++++++++
> > .../uapi/linux/media/dreamchip/rppx1-config.h | 48 +++++++++++++++-
> > 4 files changed, 108 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/media/platform/dreamchip/rppx1/rpp_module.h b/drivers/media/platform/dreamchip/rppx1/rpp_module.h
> > index 136ec4d48054..27235fdfb749 100644
> > --- a/drivers/media/platform/dreamchip/rppx1/rpp_module.h
> > +++ b/drivers/media/platform/dreamchip/rppx1/rpp_module.h
> > @@ -86,6 +86,7 @@ void rpp_module_clrset(struct rpp_module *mod, u32 offset, u32 mask, u32 value);
> > union rppx1_params_block {
> > struct v4l2_isp_params_block_header header;
> > struct rppx1_bls_params bls;
> > + struct rppx1_lin_params lin;
> > struct rppx1_lsc_params lsc;
> > struct rppx1_awbg_params awbg;
> > struct rppx1_bd_params bd;
> > diff --git a/drivers/media/platform/dreamchip/rppx1/rpp_params.c b/drivers/media/platform/dreamchip/rppx1/rpp_params.c
> > index edea25293d64..1995a80890f4 100644
> > --- a/drivers/media/platform/dreamchip/rppx1/rpp_params.c
> > +++ b/drivers/media/platform/dreamchip/rppx1/rpp_params.c
> > @@ -18,6 +18,8 @@ static const struct v4l2_isp_block_type_info
> > rppx1_ext_params_blocks_info[] = {
> > RPPX1_PARAMS_BLOCK_INFO(BLS_PRE1, bls),
> > RPPX1_PARAMS_BLOCK_INFO(BLS_PRE2, bls),
> > + RPPX1_PARAMS_BLOCK_INFO(LIN_PRE1, lin),
> > + RPPX1_PARAMS_BLOCK_INFO(LIN_PRE2, lin),
> > RPPX1_PARAMS_BLOCK_INFO(LSC_PRE1, lsc),
> > RPPX1_PARAMS_BLOCK_INFO(LSC_PRE2, lsc),
> > RPPX1_PARAMS_BLOCK_INFO(AWBG_PRE1, awbg),
> > @@ -72,6 +74,9 @@ int rppx1_params(struct rppx1 *rpp, struct vb2_buffer *vb, size_t max_size,
> > case RPPX1_PARAMS_BLOCK_TYPE_BLS_PRE1:
> > module = &rpp->pre1.bls;
> > break;
> > + case RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE1:
> > + module = &rpp->pre1.lin;
> > + break;
> > case RPPX1_PARAMS_BLOCK_TYPE_LSC_PRE1:
> > module = &rpp->pre1.lsc;
> > break;
> > diff --git a/drivers/media/platform/dreamchip/rppx1/rppx1_lin.c b/drivers/media/platform/dreamchip/rppx1/rppx1_lin.c
> > index f595f56a292e..cc8efe3b3f2c 100644
> > --- a/drivers/media/platform/dreamchip/rppx1/rppx1_lin.c
> > +++ b/drivers/media/platform/dreamchip/rppx1/rppx1_lin.c
> > @@ -24,6 +24,11 @@
> > #define LIN_B_Y_REG_NUM 17
> > #define LIN_B_Y_REG(n) (0x0098 + (4 * (n)))
> >
> > +#define LIN_PRE1_DEGAMMA_CURVE_MASK GENMASK(23, 0)
> > +#define LIN_PRE1_SAMPLE_POINTS_MASK GENMASK(3, 0)
> > +#define LIN_PRE2_DEGAMMA_CURVE_MASK GENMASK(11, 0)
> > +#define LIN_PRE2_SAMPLE_POINTS_MASK GENMASK(2, 0)
> > +
> > static int rppx1_lin_probe(struct rpp_module *mod)
> > {
> > /* Version check. */
> > @@ -52,7 +57,57 @@ static int rppx1_lin_start(struct rpp_module *mod,
> > return 0;
> > }
> >
> > +static int rppx1_lin_fill_params(struct rpp_module *mod,
> > + const union rppx1_params_block *block,
> > + rppx1_reg_write write, void *priv)
> > +{
> > + const struct rppx1_lin_params *cfg = &block->lin;
> > + u8 sample_mask;
> > + u32 mask;
> > +
> > + if (cfg->header.flags & V4L2_ISP_PARAMS_FL_BLOCK_DISABLE) {
> > + write(priv, mod->base + LIN_ENABLE_REG, 0);
> > + return 0;
> > + }
> > +
> > + switch (cfg->header.type) {
> > + case RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE1:
> > + mask = LIN_PRE1_DEGAMMA_CURVE_MASK;
> > + sample_mask = LIN_PRE1_SAMPLE_POINTS_MASK;
> > + break;
> > + case RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE2:
> > + mask = LIN_PRE2_DEGAMMA_CURVE_MASK;
> > + sample_mask = LIN_PRE2_SAMPLE_POINTS_MASK;
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > +
> > + u32 dx_lo = 0;
> > + u32 dx_hi = 0;
>
> I was clearly over-excited by the modernity of C99 that allows mixing
> declarations and code. However this is still a discouraged practice
> unless there are good reasons to do so. Probably in this case there
> aren't enough.
Fixed.
>
> > +
> > + for (unsigned int i = 0; i < 8; ++i) {
> > + dx_lo |= (cfg->dx[i] & sample_mask) << 4 * i;
> > + dx_hi |= (cfg->dx[i + 8] & sample_mask) << 4 * i;
> > + }
> > +
> > + write(priv, mod->base + LIN_DX_LO_REG, dx_lo);
> > + write(priv, mod->base + LIN_DX_HI_REG, dx_hi);
> > +
> > + for (unsigned int i = 0; i < RPPX1_LIN_DEGAMMA_CURVE_NUM; i++) {
> > + write(priv, mod->base + LIN_R_Y_REG(i), cfg->curve_r[i] & mask);
> > + write(priv, mod->base + LIN_G_Y_REG(i), cfg->curve_g[i] & mask);
> > + write(priv, mod->base + LIN_B_Y_REG(i), cfg->curve_b[i] & mask);
> > + }
> > +
> > + if ((cfg->header.flags & V4L2_ISP_PARAMS_FL_BLOCK_ENABLE))
> > + write(priv, mod->base + LIN_ENABLE_REG, LIN_ENABLE_GAMMA_IN_EN);
> > +
> > + return 0;
> > +}
> > +
> > const struct rpp_module_ops rppx1_lin_ops = {
> > .probe = rppx1_lin_probe,
> > .start = rppx1_lin_start,
> > + .fill_params = rppx1_lin_fill_params,
> > };
> > diff --git a/include/uapi/linux/media/dreamchip/rppx1-config.h b/include/uapi/linux/media/dreamchip/rppx1-config.h
> > index 0246e9af1d1d..e743e11d11e9 100644
> > --- a/include/uapi/linux/media/dreamchip/rppx1-config.h
> > +++ b/include/uapi/linux/media/dreamchip/rppx1-config.h
> > @@ -95,6 +95,8 @@ enum rppx1_meas_chan {
> > * @RPPX1_PARAMS_BLOCK_TYPE_DB_FILTER_POST: Debayer filtering
> > * @RPPX1_PARAMS_BLOCK_TYPE_BD_PRE1: PRE1 pipe De-noise Pre-Filter
> > * @RPPX1_PARAMS_BLOCK_TYPE_BD_PRE2: PRE2 pipe De-noise Pre-Filter
> > + * @RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE1: PRE1 pipe Linearization (Sensor De-gamma)
> > + * @RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE2: PRE2 pipe Linearization (Sensor De-gamma)
> > */
> > enum rppx1_params_block_type {
> > RPPX1_PARAMS_BLOCK_TYPE_WBMEAS_POST,
> > @@ -117,6 +119,8 @@ enum rppx1_params_block_type {
> > RPPX1_PARAMS_BLOCK_TYPE_DB_FILTER_POST,
> > RPPX1_PARAMS_BLOCK_TYPE_BD_PRE1,
> > RPPX1_PARAMS_BLOCK_TYPE_BD_PRE2,
> > + RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE1,
> > + RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE2,
> > };
> >
> > /**
> > @@ -735,6 +739,46 @@ struct rppx1_bd_params {
> > struct rppx1_bd_nll nll;
> > };
> >
> > +/* Linearization (Sensor De-gamma) */
> > +#define RPPX1_LIN_SAMPLE_POINTS_NUM 16
> > +#define RPPX1_LIN_DEGAMMA_CURVE_NUM 17
> > +
> > +/**
> > + * struct rppx1_lin_params - Linearization (Sensor De-gamma) configuration
> > + *
> > + * The RPP-X1 linearization module is available on the PRE1 and PRE2 pre-fusion
> > + * pipes. Userspace selects which pipe to operate by setting the @header.type
> > + * field to RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE1 or
> > + * RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE2.
> > + *
> > + * The LIN module applies the per-color channel de-gamma linearization curves
> > + * @curve_r, @curve_g and @curve_b defined on the input sampling points @dx.
> > + *
> > + * For the PRE1 pipe the de-gamma curves values are 24-bits, for the PRE2 pipe
> > + * the de-gamma curve values are 12-bits.
> > + *
> > + * For the PRE1 pipe de-gamma module sampling points @dx values are in the range
> > + * [0, 15] (4 bits). For the PRE2 pipe de-gamma module sampling points values
> > + * are in the range [0, 7] (3 bits).
> > + *
> > + * Userspace is expected to provide the curve values and sampling points with a
> > + * bit-depth matching the one of pipe in use.
> > + *
> > + * @header: block header (type = RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE1 or
> > + * RPPX1_PARAMS_BLOCK_TYPE_LIN_PRE2)
> > + * @curve_r: de-gamma linearization curve for red channel
> > + * @curve_g: de-gamma linearization curve for green channel
> > + * @curve_b: de-gamma linearization curve for blue channel
> > + * @dx: input sampling points
> > + */
> > +struct rppx1_lin_params {
> > + struct v4l2_isp_params_block_header header;
> > + __u32 curve_r[RPPX1_LIN_DEGAMMA_CURVE_NUM];
> > + __u32 curve_g[RPPX1_LIN_DEGAMMA_CURVE_NUM];
> > + __u32 curve_b[RPPX1_LIN_DEGAMMA_CURVE_NUM];
> > + __u8 dx[RPPX1_LIN_SAMPLE_POINTS_NUM];
> > +};
> > +
> > /**
> > * RPPX1_PARAMS_MAX_SIZE - Maximum size of all RPP-X1 parameter blocks
> > *
> > @@ -761,7 +805,9 @@ struct rppx1_bd_params {
> > sizeof(struct rppx1_db_demosaic_params) + \
> > sizeof(struct rppx1_db_filter_params) + \
> > sizeof(struct rppx1_bd_params) + \
> > - sizeof(struct rppx1_bd_params))
> > + sizeof(struct rppx1_bd_params) + \
> > + sizeof(struct rppx1_lin_params) + \
> > + sizeof(struct rppx1_lin_params))
> >
> > /* ---------------------------------------------------------------------------
> > * Statistics Structures
> > --
> > 2.54.0
> >
> >
--
Kind Regards,
Niklas Söderlund