Re: [REBASE 5/7] drm/edid: avoid drm_edid_find_extension() internally

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

On Tue, 16 Apr 2024, Thomas Zimmermann <tzimmermann@suse.de> wrote:
> Hi
>
> Am 16.04.24 um 11:19 schrieb Jani Nikula:
>> Prefer the EDID iterators over drm_edid_find_extension() in
>> drm_edid_has_cta_extension(), even if this leads to more code. The key
>> is to use the same patterns as much as possible.
>
> Should this patch go before patch 4? That would limit the impact of the 
> latter.

I can if you want, IMO not a big deal.

> Why is this instance different than the one in 
> drm_find_displayid_extension()? Best regards Thomas

Overall I'd like to get rid of the function altogether, but I'm
undecided what the replacement interface towards drm_displayid.c should
be. Maybe expose the drm_edid_iter_* stuff? But I really don't want
anyone to export and start using them in drivers.

BR,
Jani.

>>
>> Signed-off-by: Jani Nikula <jani.nikula@intel.com>
>> ---
>>   drivers/gpu/drm/drm_edid.c | 14 ++++++++++++--
>>   1 file changed, 12 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
>> index c29f31dcc818..4b3ad42a8f95 100644
>> --- a/drivers/gpu/drm/drm_edid.c
>> +++ b/drivers/gpu/drm/drm_edid.c
>> @@ -4230,11 +4230,21 @@ static bool drm_edid_has_cta_extension(const struct drm_edid *drm_edid)
>>   {
>>   	const struct displayid_block *block;
>>   	struct displayid_iter iter;
>> -	int ext_index = 0;
>> +	struct drm_edid_iter edid_iter;
>> +	const u8 *ext;
>>   	bool found = false;
>>   
>>   	/* Look for a top level CEA extension block */
>> -	if (drm_edid_find_extension(drm_edid, CEA_EXT, &ext_index))
>> +	drm_edid_iter_begin(drm_edid, &edid_iter);
>> +	drm_edid_iter_for_each(ext, &edid_iter) {
>> +		if (ext[0] == CEA_EXT) {
>> +			found = true;
>> +			break;
>> +		}
>> +	}
>> +	drm_edid_iter_end(&edid_iter);
>> +
>> +	if (found)
>>   		return true;
>>   
>>   	/* CEA blocks can also be found embedded in a DisplayID block */

-- 
Jani Nikula, Intel