[PATCH v2 12/14] drm/edid: introduce a helper that compares edid data from two drm_edid

[Jani Nikula]

On Tue, 06 May 2025, Melissa Wen <mwen at igalia.com> wrote:
> AMD driver has a function used to compare if two edid are the same; this
> is useful to some of the link detection algorithms implemented by
> amdgpu. Since the amdgpu function can be helpful for other drivers, this
         ^

Theres's a non-breaking space in there I think.

> commit abstracts the AMD function to make it available at the DRM level
> by wrapping existent drm_edid_eq().
>
> v2:
> - rename drm_edid_eq to drm_edid_eq_buf (jani)
> - add NULL checks (jani)
>
> Co-developed-by: Rodrigo Siqueira <siqueira at igalia.com>
> Signed-off-by: Rodrigo Siqueira <siqueira at igalia.com>
> Signed-off-by: Melissa Wen <mwen at igalia.com>
> ---
>  drivers/gpu/drm/drm_edid.c | 24 +++++++++++++++++++++---
>  include/drm/drm_edid.h     |  2 ++
>  2 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 6e4cffd467f1..079042ccbc41 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -1820,8 +1820,8 @@ static bool edid_block_is_zero(const void *edid)
>  	return mem_is_zero(edid, EDID_LENGTH);
>  }
>  
> -static bool drm_edid_eq(const struct drm_edid *drm_edid,
> -			const void *raw_edid, size_t raw_edid_size)
> +static bool drm_edid_eq_buf(const struct drm_edid *drm_edid,
> +			    const void *raw_edid, size_t raw_edid_size)
>  {
>  	bool edid1_present = drm_edid && drm_edid->edid && drm_edid->size;
>  	bool edid2_present = raw_edid && raw_edid_size;
> @@ -6918,7 +6918,7 @@ static int _drm_edid_connector_property_update(struct drm_connector *connector,
>  		const void *old_edid = connector->edid_blob_ptr->data;
>  		size_t old_edid_size = connector->edid_blob_ptr->length;
>  
> -		if (old_edid && !drm_edid_eq(drm_edid, old_edid, old_edid_size)) {
> +		if (old_edid && !drm_edid_eq_buf(drm_edid, old_edid, old_edid_size)) {
>  			connector->epoch_counter++;
>  			drm_dbg_kms(dev, "[CONNECTOR:%d:%s] EDID changed, epoch counter %llu\n",
>  				    connector->base.id, connector->name,
> @@ -7523,3 +7523,21 @@ bool drm_edid_is_digital(const struct drm_edid *drm_edid)
>  		drm_edid->edid->input & DRM_EDID_INPUT_DIGITAL;
>  }
>  EXPORT_SYMBOL(drm_edid_is_digital);
> +
> +/**
> + * drm_edid_edid_eq - Check if EDIDs are equal
> + *
> + * @drm_edid_old: old drm_edid to compare edid
> + * @drm_edid_new: new drm_edid to compare edid

Comments still refer to old/new, please run kernel-doc.

> + *
> + * Return true if EDIDs are equal.
> + */
> +bool drm_edid_eq(const struct drm_edid *drm_edid_1,
> +		 const struct drm_edid *drm_edid_2)
> +{
> +	const void *edid_1 = drm_edid_1 ? drm_edid_1->edid : NULL;
> +	size_t edid_1_size = drm_edid_1 ? drm_edid_1->size : 0;
> +
> +	return drm_edid_eq_buf(drm_edid_2, edid_1, edid_1_size);
> +}
> +EXPORT_SYMBOL(drm_edid_eq);
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index ceb522c4f4c2..c0e49c4a32e9 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -472,6 +472,8 @@ int drm_edid_connector_update(struct drm_connector *connector,
>  			      const struct drm_edid *edid);
>  int drm_edid_connector_add_modes(struct drm_connector *connector);
>  bool drm_edid_is_digital(const struct drm_edid *drm_edid);
> +bool drm_edid_eq(const struct drm_edid *drm_edid_first,
> +			 const struct drm_edid *drm_edid_second);

Nitpick, parameter names in the declaration differ from the ones in the
definition.

With the above fixed,

Reviewed-by: Jani Nikula <jani.nikula at intel.com>


>  void drm_edid_get_product_id(const struct drm_edid *drm_edid,
>  			     struct drm_edid_product_id *id);
>  void drm_edid_print_product_id(struct drm_printer *p,

-- 
Jani Nikula, Intel