Re: [PATCH RFC 4/4] media: qcom: camss: vfe: Add the IFE 780 pixel pipe description

[bod]

On 2026-10-13 09:44 +0100, William Bright wrote:
> The IFE 780 WB gain registers only take bits 31:17. A Q10 gain there
> reaches full scale at 1.0, while the 0x1000 used on the IFE 880 reads
> back as zero and every frame comes out black.
> 
> Its demosaic also leaks red and blue into green whenever green sits on
> a black level pedestal. With AR1335 colour bars magenta comes out white
> and red and blue pick up half scale green. Subtracting the black level
> in demux + BLS fixes it.
> 
> Describe both and use the description on SM8550.
> 
> Assisted-by: Claude:claude-opus-5-5
> Signed-off-by: William Bright <william.bright@xxxxxxxxxxx>
> ---
>  drivers/media/platform/qcom/camss/camss-vfe-780.c    | 3 +++
>  drivers/media/platform/qcom/camss/camss-vfe-880-pp.c | 6 ++++++
>  drivers/media/platform/qcom/camss/camss-vfe-880-pp.h | 1 +
>  3 files changed, 10 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/camss/camss-vfe-780.c b/drivers/media/platform/qcom/camss/camss-vfe-780.c
> index 032786c4ed74..63fee6ab64fe 100644
> --- a/drivers/media/platform/qcom/camss/camss-vfe-780.c
> +++ b/drivers/media/platform/qcom/camss/camss-vfe-780.c
> @@ -238,6 +238,9 @@ static inline void vfe_reg_update_clear(struct vfe_device *vfe,
>   */
>  static const struct vfe_pp_desc *vfe_pp_desc(struct vfe_device *vfe)
>  {
> +	if (vfe->camss->res->version == CAMSS_8550)
> +		return &vfe_pp_desc_780;
> +
>  	return &vfe_pp_desc_880;
>  }

Thanks for this RFC its a good feed-in for V1.

I will try to cherry-pick/incorporate this in the V1.
---
bod