Re: [PATCH v3 10/13] media: stm32: dcmipp: pixelproc: addition of dcmipp-pixelproc subdev

Hi Hans,

thanks for the review,

On Mon, Jul 27, 2026 at 03:49:38PM +0200, Hans Verkuil wrote:
> Hi Alain,
> 
> Some control-related comments:
> 
> On 24/07/2026 18:13, Alain Volmat wrote:
> > Addition of the driver for dcmipp-pixelproc subdev.  This subdev is the
> > last one before the capture device at the tail of both main and
> > aux pipelines.
> > 
> > It is in charge of:
> >   - framerate adjustment
> >   - downscale
> >   - gamma correction
> >   - color conversion
> >   - pixel packing
> > 
> > Signed-off-by: Alain Volmat <[email protected]>
> > ---
> >  .../media/platform/st/stm32/stm32-dcmipp/Makefile  |   2 +-
> >  .../platform/st/stm32/stm32-dcmipp/dcmipp-common.h |   4 +
> >  .../st/stm32/stm32-dcmipp/dcmipp-pixelproc.c       | 941 +++++++++++++++++++++
> >  3 files changed, 946 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/Makefile b/drivers/media/platform/st/stm32/stm32-dcmipp/Makefile
> > index a708534a51af4..7178934bb116b 100644
> > --- a/drivers/media/platform/st/stm32/stm32-dcmipp/Makefile
> > +++ b/drivers/media/platform/st/stm32/stm32-dcmipp/Makefile
> > @@ -1,5 +1,5 @@
> >  # SPDX-License-Identifier: GPL-2.0
> >  stm32-dcmipp-y := dcmipp-core.o dcmipp-common.o dcmipp-input.o dcmipp-byteproc.o dcmipp-bytecap.o
> > -stm32-dcmipp-y += dcmipp-pixelcommon.o dcmipp-isp.o
> > +stm32-dcmipp-y += dcmipp-pixelcommon.o dcmipp-isp.o dcmipp-pixelproc.o
> >  
> >  obj-$(CONFIG_VIDEO_STM32_DCMIPP) += stm32-dcmipp.o
> > diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-common.h b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-common.h
> > index e04fde86550a5..8f41473605aae 100644
> > --- a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-common.h
> > +++ b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-common.h
> > @@ -285,5 +285,9 @@ void dcmipp_bytecap_ent_release(struct dcmipp_ent_device *ved);
> >  struct dcmipp_ent_device *dcmipp_isp_ent_init(const char *entity_name,
> >  					      struct dcmipp_device *dcmipp);
> >  void dcmipp_isp_ent_release(struct dcmipp_ent_device *ved);
> > +struct dcmipp_ent_device *
> > +dcmipp_pixelproc_ent_init(const char *entity_name,
> > +			  struct dcmipp_device *dcmipp);
> > +void dcmipp_pixelproc_ent_release(struct dcmipp_ent_device *ved);
> >  
> >  #endif
> > diff --git a/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-pixelproc.c b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-pixelproc.c
> > new file mode 100644
> > index 0000000000000..4372c75508725
> > --- /dev/null
> > +++ b/drivers/media/platform/st/stm32/stm32-dcmipp/dcmipp-pixelproc.c
> 
> <snip>
> 
> > +/*
> > + * Functions handling controls
> > + */
> > +#define V4L2_CID_PIXELPROC_GAMMA_CORRECTION	(V4L2_CID_USER_BASE | 0x1001)
> 
> You need to reserve a range in include/uapi/linux/v4l2-controls.h for this
> driver (search for V4L2_CID_USER_MALI_C55_BASE).

Done in v4.

> 
> And the define should include the driver name. 'PIXELPROC' is much too generic.
> It probably should be called DCMIPP_PIXELPROC.

Done in v4.

> Please document what this control does. Typically a new header is added to
> include/linux/uapi for this driver containing the CID and the documentation.
> See: include/uapi/linux/dw100.h

Looking at other drivers such as raspberry etc, they seems to have their
header in include/uapi/linux/media/xx so I added a new header include/uapi/linux/media/st/dcmipp_config.h

> 
> > +
> > +static int dcmipp_pixelproc_s_ctrl(struct v4l2_ctrl *ctrl)
> > +{
> > +	struct dcmipp_pixelproc_device *pixelproc =
> > +		container_of(ctrl->handler,
> > +			     struct dcmipp_pixelproc_device, ctrls);
> > +
> > +	if (!pm_runtime_get_if_in_use(pixelproc->dev))
> > +		return 0;
> > +
> > +	switch (ctrl->id) {
> > +	case V4L2_CID_PIXELPROC_GAMMA_CORRECTION:
> > +		reg_write(pixelproc, DCMIPP_PxGMCR(pixelproc->pipe_id),
> > +			  (ctrl->val ? DCMIPP_PxGMCR_ENABLE : 0));
> > +		break;
> > +	}
> > +
> > +	pm_runtime_put(pixelproc->dev);
> > +
> > +	return 0;
> > +};
> > +
> > +static const struct v4l2_ctrl_ops dcmipp_pixelproc_ctrl_ops = {
> > +	.s_ctrl = dcmipp_pixelproc_s_ctrl,
> > +};
> > +
> > +static const struct v4l2_ctrl_config dcmipp_pixelproc_ctrls[] = {
> > +	{
> > +		.ops		= &dcmipp_pixelproc_ctrl_ops,
> > +		.id		= V4L2_CID_PIXELPROC_GAMMA_CORRECTION,
> > +		.type		= V4L2_CTRL_TYPE_BOOLEAN,
> > +		.name		= "Gamma correction",
> 
> "Gamma Correction". More likely, "Gamma Correction Enable" (and ENABLE should probably
> be in the CID define as well).

Done in v4.

Regards,
Alain