[PATCH v13 15/15] Documentation: mali-c55: Document the mali-c55 parameter setting

[Sakari Ailus]

Hi Jacopo,

On Thu, Nov 13, 2025 at 09:39:37AM +0100, Jacopo Mondi wrote:
> > +the data member with the blocks that need to be configured by the driver, but
> > +need not populate it with **all** the blocks, or indeed with any at all if there
> > +are no configuration changes to make. Populated blocks **must** be consecutive
> > +in the buffer. To assist both userspace and the driver in identifying the
> > +blocks each block-specific struct embeds :c:type:`v4l2_params_block_header` as
> > +its first member and userspace must populate the type member with a value from
> > +:c:type:`mali_c55_param_block_type`. Once the blocks have been populated
> > +into the data buffer, the combined size of all populated blocks shall be set in
> > +the data_size member of :c:type:`v4l2_params_buffer`. For example:
> > +
> > +.. code-block:: c
> > +
> > +	struct v4l2_params_buffer *params =
> > +		(struct v4l2_params_buffer *)buffer;
> > +
> > +	params->version = MALI_C55_PARAM_BUFFER_V1;
> > +	params->data_size = 0;
> > +
> > +	void *data = (void *)params->data;
> > +
> > +	struct mali_c55_params_awb_gains *gains =
> > +		(struct mali_c55_params_awb_gains *)data;
> > +
> > +	gains->header.type = MALI_C55_PARAM_BLOCK_AWB_GAINS;
> > +	gains->header.flags |= V4L2_PARAMS_FL_BLOCK_ENABLE;
> > +	gains->header.size = sizeof(struct mali_c55_params_awb_gains);
> > +
> > +	gains->gain00 = 256;
> > +	gains->gain00 = 256;
> > +	gains->gain00 = 256;
> > +	gains->gain00 = 256;
> > +
> > +	data += sizeof(struct mali_c55_params_awb_gains);
> > +	params->data_size += sizeof(struct mali_c55_params_awb_gains);
> > +
> > +	struct mali_c55_params_sensor_off_preshading *blc =
> > +		(struct mali_c55_params_sensor_off_preshading *)data;
> > +
> > +	blc->header.type = MALI_C55_PARAM_BLOCK_SENSOR_OFFS;
> > +	blc->header.flags |= V4L2_PARAMS_FL_BLOCK_ENABLE;
> > +	blc->header.size = sizeof(struct mali_c55_params_sensor_off_preshading);
> > +
> > +	blc->chan00 = 51200;
> > +	blc->chan01 = 51200;
> > +	blc->chan10 = 51200;
> > +	blc->chan11 = 51200;
> > +
> > +	params->total_size += sizeof(struct mali_c55_params_sensor_off_preshading);
> 
> s/total_size/data_size
> 
> And I've also updated it to use the v4l2-isp types
> 
> +.. code-block:: c
> +
> +       struct v4l2_isp_params_buffer *params =
> +               (struct v4l2_isp_params_buffer *)buffer;

What's the type of buffer here? If it's void, you can drop the cast.

> +
> +       params->version = MALI_C55_PARAM_BUFFER_V1;
> +       params->data_size = 0;
> +
> +       void *data = (void *)params->data;

No need for a cast here.

> +
> +       struct mali_c55_params_awb_gains *gains =
> +               (struct mali_c55_params_awb_gains *)data;

Ditto.

Unless, I guess, you use C++. :-)

> +
> +       gains->header.type = MALI_C55_PARAM_BLOCK_AWB_GAINS;
> +       gains->header.flags |= V4L2_ISP_PARAMS_FL_BLOCK_ENABLE;
> +       gains->header.size = sizeof(struct mali_c55_params_awb_gains);
> +
> +       gains->gain00 = 256;
> +       gains->gain00 = 256;
> +       gains->gain00 = 256;
> +       gains->gain00 = 256;
> +
> +       data += sizeof(struct mali_c55_params_awb_gains);

	data += sizeof(*gains);

?

> +       params->data_size += sizeof(struct mali_c55_params_awb_gains);

Ditto.

> +
> +       struct mali_c55_params_sensor_off_preshading *blc =
> +               (struct mali_c55_params_sensor_off_preshading *)data;
> +
> +       blc->header.type = MALI_C55_PARAM_BLOCK_SENSOR_OFFS;
> +       blc->header.flags |= V4L2_ISP_PARAMS_FL_BLOCK_ENABLE;
> +       blc->header.size = sizeof(struct mali_c55_params_sensor_off_preshading);
> +
> +       blc->chan00 = 51200;
> +       blc->chan01 = 51200;
> +       blc->chan10 = 51200;
> +       blc->chan11 = 51200;
> +
> +       params->data_size += sizeof(struct mali_c55_params_sensor_off_preshading);

	... += sizeof(*blc);

?

> 
> With your ack, I'll apply the following changes before sending the PR.
> 
> Thanks
>   j
> 
> > +
> >  Arm Mali-C55 uAPI data types
> >  ============================
> >
> >

-- 
Regards,

Sakari Ailus