Hi Bryan,
On Tue, Sep 15, 2026 at 11:11 AM Bryan O'Donoghue
<[email protected]> wrote:
>
> On 15/09/2026 09:11, Loic Poulain wrote:
> > Add the uapi header qcom-camss-config.h defining the ISP parameter
> > structures used by the CAMSS Offline Processing Engine (OPE) driver.
> > This includes structures for white balance, chroma enhancement and
> > color correction configuration.
> >
> > The block type enum is shared across CAMSS ISPs so that userspace only
> > has to deal with a single set of block identifiers.
> >
> > Signed-off-by: Loic Poulain <[email protected]>
> > ---
> > include/uapi/linux/qcom-camss-config.h | 212
> > +++++++++++++++++++++++++++++++++
> > 1 file changed, 212 insertions(+)
> >
> > diff --git a/include/uapi/linux/qcom-camss-config.h
> > b/include/uapi/linux/qcom-camss-config.h
> > new file mode 100644
> > index
> > 0000000000000000000000000000000000000000..e3d6cc4df7de00345e8142c81392dd42338c6ead
> > --- /dev/null
> > +++ b/include/uapi/linux/qcom-camss-config.h
> > @@ -0,0 +1,212 @@
> > +/* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
> > +/*
> > + * Qualcomm CAMSS ISP Driver - Userspace API
> > + *
> > + * Copyright (c) Qualcomm Technologies, Inc. and/or its subsidiaries.
> > + */
> > +
> > +#ifndef _UAPI_LINUX_QCOM_CAMSS_CONFIG_H
> > +#define _UAPI_LINUX_QCOM_CAMSS_CONFIG_H
> > +
> > +#include <linux/types.h>
> > +#include <linux/media/v4l2-isp.h>
> > +
> > +/**
> > + * enum camss_params_block_type - CAMSS ISP parameter block identifiers
> > + *
> > + * Each value identifies one ISP processing block. The value is placed in
> > + * the @type field of &struct v4l2_isp_params_block_header.
> > + *
> > + * @CAMSS_PARAMS_OPE_WB_GAIN: white balance gains and offsets (CLC_WB),
> > + * &struct camss_params_ope_wb_gain
> > + * @CAMSS_PARAMS_OPE_CHROMA_ENHAN: RGB to YUV colour transfer matrix
> > + * (CLC_CHROMA_ENHAN), &struct camss_params_ope_chroma_enhan
> > + * @CAMSS_PARAMS_OPE_COLOR_CORRECT: colour correction matrix (CLC_CC),
> > + * &struct camss_params_ope_color_correct
> > + * @CAMSS_PARAMS_OPE_GAMMA: per-channel gamma correction curves (CLC_GLUT),
> > + * &struct camss_params_ope_gamma
> > + */
> > +enum camss_params_block_type {
> > + CAMSS_PARAMS_OPE_WB_GAIN = 1,
> > + CAMSS_PARAMS_OPE_CHROMA_ENHAN = 2,
> > + CAMSS_PARAMS_OPE_COLOR_CORRECT = 3,
> > + CAMSS_PARAMS_OPE_GAMMA = 4,
> > +};
>
> Most of the OPE specific naming can be dropped, I shared the ICP
> data-structure analysis already:
>
> https://patchwork.linuxtv.org/project/linux-media/patch/[email protected]/
Ok, I thought we agreed on having OPE specific structures, that is why
I recently moved everything to OPE specific name.
>
> i.e.
> > +struct camss_params_ope_color_correct {
> > + struct v4l2_isp_params_block_header header;
> > + __u16 a[3];
> > + __u16 b[3];
> > + __u16 c[3];
> > + __u16 k[3];
> > + __u16 qfactor;
> > + __u16 _pad[3];
> > +} __attribute__((aligned(8)));
>
> For ICP I have:
>
> +struct camss_params_color_correct {
> + struct v4l2_isp_params_block_header header;
> + __u16 a[3];
> + __u16 b[3];
> + __u16 c[3];
> + __u16 k[3];
> + __u16 qfactor;
> + __u16 _pad[3];
> +} __attribute__((aligned(8)));
>
> So this data-structure is shared camss_params_ope_color_correct ->
> camss_params_color_correct
Ack.
Also, I will remove the _ope_ suffix from the wb_gain and
color_correct structures. These structures may differ or even be
absent in the ICP case, but they should remain aligned with the IFE
implementation since both use the same underlying blocks.
>
> > +/**
> > + * struct camss_params_ope_gamma - per-channel gamma correction curves
> > + *
> > + * Implements the CLC_GLUT pipeline module, applied in the RGB domain. It
> > + * holds one independent lookup table per colour channel. Each table is a
> > + * direct (not segmented) map of input level to output level.
> > + *
> > + * Each table has @CAMSS_OPE_GAMMA_LUT_SIZE (256) entries of 16-bit
> > unsigned
> > + * output. Each entry holds an X-bit output value depending on internal
> > bus,
> > + * the upper bits are ignored by the hardware.
> > + *
> > + * On Agatti OPE, The module maps a 12-bit input to an 8-bit output, the
> > top
> > + * 8 input bits index the table and the low 4 bits are used to linearly
> > + * interpolate between adjacent entries. Entry i therefore represents the
> > + * output for input level i/255 of full scale.
> > + * Output range: 0x00 = black, 0xFF = white.
>
> That's not specific to Agatti, its hwo the Qcom gamma silicon works right ?
Yes, as far as I know. However, we may observe some variation if the
internal bus width changes.
Considering the hardware platforms we currently support with OPE, as
well as the upcoming platforms, I think we can treat this as a generic
assumption for now.
> Same RTL synthesised in OPE, IPE and IFE. So you don't need to make this
> OPE specific commentary.
Ack.
>
> > + *
> > + * How to fill a curve (same on all three channels for pure luminance
> > + * gamma; different curves per channel additionally shift colour balance):
> > + *
> > + * Identity (pass-through, gamma 1.0):
> > + * lut[i] = i; // i = 0..255
> > + *
> > + * Encode with gamma g (e.g. sRGB-like, g = 2.2):
> > + * lut[i] = round(pow(i / 255.0, 1.0 / g) * 255.0);
> > + *
> > + * @header: block header; @header.type = CAMSS_PARAMS_OPE_GAMMA
> > + * @glut: green channel gamma curve
> > + * @blut: blue channel gamma curve
> > + * @rlut: red channel gamma curve
> > + */
> > +struct camss_params_ope_gamma {
> > + struct v4l2_isp_params_block_header header;
> > + __u16 glut[CAMSS_OPE_GAMMA_LUT_SIZE];
> > + __u16 blut[CAMSS_OPE_GAMMA_LUT_SIZE];
> > + __u16 rlut[CAMSS_OPE_GAMMA_LUT_SIZE];
> > +} __attribute__((aligned(8)));
>
> For the ICP I have
>
> +struct camss_params_glut {
> + struct v4l2_isp_params_block_header header;
> + __u8 instance;
> + __u8 _pad[7];
> + __u16 r[CAMSS_GLUT_LUT_SIZE];
> + __u16 g[CAMSS_GLUT_LUT_SIZE];
> + __u16 b[CAMSS_GLUT_LUT_SIZE];
> +} __attribute__((aligned(8)));
>
> So it makes more sense to differentiate the firmware type to the
> register-mapping type. i.e. the above becomes camss_params_icp_gamma {}
> whereas your subumitted change would be just camss_params_gamma {}
ok!
>
> > +#define CAMSS_PARAMS_OPE_MAX_PAYLOAD \
> > + (sizeof(struct camss_params_ope_wb_gain) +\
> > + sizeof(struct camss_params_ope_chroma_enhan) +\
> > + sizeof(struct camss_params_ope_color_correct) +\
> > + sizeof(struct camss_params_ope_gamma))
> > +
> > +#endif /* _UAPI_LINUX_QCOM_CAMSS_CONFIG_H */
> >
>
