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

[Melissa Wen]

On 08/05/2025 08:47, Jani Nikula wrote:
> 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>

Oops. I'll address all comments in the next version.

Thanks,

Melissa
>
>
>>   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,