Re: [PATCH v2 1/2] drm/edid: Export drm_edid_block_count()

[Jani Nikula <jani.nikula@linux.intel.com>]

On Mon, 13 Jul 2026, Timo Prömer <timo.proemer04@gmail.com> wrote:
> From: Timoyoungster <timo.proemer04@gmail.com>
>
> Drivers currently calculating EDID size by reading the `extensions`
> field of the raw EDID structure (e.g., `edid->extensions + 1`) will
> calculate the wrong size if the EDID contains an HF-EEODB (HDMI Forum
> EDID Extension Override Data Block). The base extension flag does not
> account for these override blocks, leading to truncated EDIDs.
>
> Remove the static declaration and export drm_edid_block_count() so
> drivers can safely query the true block count. This allows drivers to
> leverage the core DRM's proper handling of HF-EEODB and other edge
> cases without having to parse the raw EDID fields themselves.
>
> Signed-off-by: Timo Prömer <timo.proemer04@gmail.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 3 ++-
>  include/drm/drm_edid.h     | 1 +
>  2 files changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index df3c25bac..34560b33a 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -1698,12 +1698,13 @@ static int __drm_edid_block_count(const struct drm_edid *drm_edid)
>  }
>  
>  /* EDID block count, limited by allocated size */
> -static int drm_edid_block_count(const struct drm_edid *drm_edid)
> +int drm_edid_block_count(const struct drm_edid *drm_edid)
>  {
>  	/* Limit by allocated size */
>  	return min(__drm_edid_block_count(drm_edid),
>  		   (int)drm_edid->size / EDID_LENGTH);
>  }
> +EXPORT_SYMBOL(drm_edid_block_count);

Not everything that's inside drm_edid.c is supposed to be looked
into. It's abstracted and hidden for a reason. Please don't hack into
this.

BR,
Jani.

>  
>  /* EDID extension block count, limited by allocated size */
>  static int drm_edid_extension_block_count(const struct drm_edid *drm_edid)
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 04f7a7f1f..4a990bf87 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -481,6 +481,7 @@ const struct drm_edid *drm_edid_read_switcheroo(struct drm_connector *connector,
>  int drm_edid_connector_update(struct drm_connector *connector,
>  			      const struct drm_edid *edid);
>  int drm_edid_connector_add_modes(struct drm_connector *connector);
> +int drm_edid_block_count(const struct drm_edid *drm_edid);
>  bool drm_edid_is_digital(const struct drm_edid *drm_edid);
>  void drm_edid_get_product_id(const struct drm_edid *drm_edid,
>  			     struct drm_edid_product_id *id);

-- 
Jani Nikula, Intel