Re: [PATCH 1/2] media: rppx1: handle the MAIN_POST white balance gains block

[Niklas Söderlund]

Hi Linmao,

Thanks for your work.

On 2026-08-17 18:45:28 +0800, Linmao Li wrote:
> RPPX1_PARAMS_BLOCK_TYPE_AWBG_POST is defined in the uAPI, the MAIN_POST
> white balance gains module is probed and started, and
> RPPX1_PARAMS_MAX_SIZE already reserves room for all three white balance
> gains blocks. However, the parameters type table has no entry for
> AWBG_POST and rppx1_params() does not dispatch it, so userspace cannot
> configure the module.
> 
> The missing type-table entry is zero-initialised. A zero-sized
> AWBG_POST block can therefore make v4l2_isp_params_validate_buffer()
> loop forever. A pending v4l2-isp patch rejects zero-sized blocks in the
> common validator.
> 
> Add the missing type entry and dispatch AWBG_POST to rpp->post.awbg.
> 
> Fixes: 9ebf50010c68 ("media: rppx1: awbg: Add support for white balance gain settings")
> Signed-off-by: Linmao Li <lilinmao@xxxxxxxxxx>
> ---
>  drivers/media/platform/dreamchip/rppx1/rpp_params.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/media/platform/dreamchip/rppx1/rpp_params.c b/drivers/media/platform/dreamchip/rppx1/rpp_params.c
> index a75a27a8afd09..88162f0bdc115 100644
> --- a/drivers/media/platform/dreamchip/rppx1/rpp_params.c
> +++ b/drivers/media/platform/dreamchip/rppx1/rpp_params.c
> @@ -25,6 +25,7 @@ rppx1_ext_params_blocks_info[] = {
>  	RPPX1_PARAMS_BLOCK_INFO(LSC_PRE2, lsc),
>  	RPPX1_PARAMS_BLOCK_INFO(AWBG_PRE1, awbg),
>  	RPPX1_PARAMS_BLOCK_INFO(AWBG_PRE2, awbg),
> +	RPPX1_PARAMS_BLOCK_INFO(AWBG_POST, awbg),

This looks good.

>  	RPPX1_PARAMS_BLOCK_INFO(CCOR_POST, ccor),
>  	RPPX1_PARAMS_BLOCK_INFO(HIST_PRE1, hist),
>  	RPPX1_PARAMS_BLOCK_INFO(HIST_PRE2, hist),
> @@ -79,6 +80,9 @@ int rppx1_params(struct rppx1 *rpp, struct vb2_buffer *vb, size_t max_size,
>  		case RPPX1_PARAMS_BLOCK_TYPE_AWBG_PRE1:
>  			module = &rpp->pre1.awbg;
>  			break;
> +		case RPPX1_PARAMS_BLOCK_TYPE_AWBG_POST:
> +			module = &rpp->post.awbg;
> +			break;

As you point out in the cover letter there are many modules, specially 
in the PRE2 pipeline, that we reserve space for in the configuration 
buffer but to not dispatch yet. But also some in the POST pipeline. The 
reason for this is that we have no users (libcamera) or test-cases for 
those blocks.

I think I would prefers keeping it like this until we do. If you really 
really want to go this path should you not also add AWBG_PRE2 here, that 
is also not dispatched ;-) But I think you should drop this and just add 
the missing entry to rppx1_ext_params_blocks_info.

>  		case RPPX1_PARAMS_BLOCK_TYPE_CCOR_POST:
>  			module = &rpp->post.ccor;
>  			break;
> -- 
> 2.25.1
> 

-- 
Kind Regards,
Niklas Söderlund