[Intel-gfx] [PATCH v2 02/15] drm/edid: abstract cea data block collection size

[Ville Syrjälä]

On Wed, Jun 08, 2022 at 10:50:32AM +0300, Jani Nikula wrote:
> Add a function to get the cea data block collection size.
> 
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/drm_edid.c | 24 +++++++++++++++++++++---
>  1 file changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index c57f6333ea7d..002816509fc8 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4482,6 +4482,20 @@ __cea_db_iter_current_block(const struct cea_db_iter *iter)
>  	return NULL;
>  }
>  
> +/*
> + * References:
> + * - CTA-861-H section 7.3.3 CTA Extension Version 3
> + */
> +static int cea_db_collection_size(const u8 *cta)
> +{
> +	u8 d = cta[2];
> +
> +	if (d < 4 || d > 127)
> +		return 0;
> +
> +	return d - 4;
> +}
> +
>  /*
>   * References:
>   * - VESA E-EDID v1.4
> @@ -4492,15 +4506,19 @@ static const void *__cea_db_iter_edid_next(struct cea_db_iter *iter)
>  	const u8 *ext;
>  
>  	drm_edid_iter_for_each(ext, &iter->edid_iter) {
> +		int size;
> +
>  		/* Only support CTA Extension revision 3+ */
>  		if (ext[0] != CEA_EXT || cea_revision(ext) < 3)
>  			continue;
>  
> -		iter->index = 4;
> -		iter->end = ext[2];
> -		if (iter->end < 4 || iter->end > 127)
> +		size = cea_db_collection_size(ext);
> +		if (!size)
>  			continue;
>  
> +		iter->index = 4;
> +		iter->end = iter->index + size;
> +
>  		return ext;
>  	}
>  
> -- 
> 2.30.2

-- 
Ville Syrjälä
Intel