Re: [Intel-gfx] [PATCH 08/15] drm/edid: add function for checking drm_edid validity

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Oct 11, 2022 at 04:49:42PM +0300, Jani Nikula wrote:
> We've lacked a function for immutable validity check on drm_edid. Add
> one.
> 
> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 30 ++++++++++++++++++++++++++++++
>  include/drm/drm_edid.h     |  1 +
>  2 files changed, 31 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 616c1cdc7507..c3cf942186b7 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -2040,6 +2040,36 @@ bool drm_edid_is_valid(struct edid *edid)
>  }
>  EXPORT_SYMBOL(drm_edid_is_valid);
>  
> +/**
> + * drm_edid_valid - sanity check EDID data
> + * @drm_edid: EDID data
> + *
> + * Sanity check an EDID. Cross check block count against allocated size and
> + * checksum the blocks.
> + *
> + * Return: True if the EDID data is valid, false otherwise.
> + */
> +bool drm_edid_valid(const struct drm_edid *drm_edid)
> +{
> +	int i;
> +
> +	if (!drm_edid)
> +		return false;
> +
> +	if (edid_size_by_blocks(__drm_edid_block_count(drm_edid)) != drm_edid->size)
> +		return false;

I Was consfued about the HF-EEODB crap for a bit but 
__drm_edid_block_count() does include that.

So looks sane
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
> +	for (i = 0; i < drm_edid_block_count(drm_edid); i++) {
> +		const void *block = drm_edid_block_data(drm_edid, i);
> +
> +		if (!edid_block_valid(block, i == 0))
> +			return false;
> +	}
> +
> +	return true;
> +}
> +EXPORT_SYMBOL(drm_edid_valid);
> +
>  static struct edid *edid_filter_invalid_blocks(struct edid *edid,
>  					       size_t *alloc_size)
>  {
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 05380681a4fb..a2e25e7e6ee5 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -606,6 +606,7 @@ drm_display_mode_from_cea_vic(struct drm_device *dev,
>  const struct drm_edid *drm_edid_alloc(const void *edid, size_t size);
>  const struct drm_edid *drm_edid_dup(const struct drm_edid *drm_edid);
>  void drm_edid_free(const struct drm_edid *drm_edid);
> +bool drm_edid_valid(const struct drm_edid *drm_edid);
>  const struct edid *drm_edid_raw(const struct drm_edid *drm_edid);
>  const struct drm_edid *drm_edid_read(struct drm_connector *connector);
>  const struct drm_edid *drm_edid_read_ddc(struct drm_connector *connector,
> -- 
> 2.34.1

-- 
Ville Syrjälä
Intel