Re: [PATCH 0/3] ASoC: cs35l41/cs35l45/cs4265: sort the reg_defaults tables

[Richard Fitzgerald <rf@opensource.cirrus.com>]

On 05/08/2026 10:52 am, Péter Ujfalusi wrote:
> 
> 
> On 05/08/2026 12:38, Richard Fitzgerald wrote:
>> On 05/08/2026 10:25 am, Charles Keepax wrote:
>>> On Wed, Aug 05, 2026 at 12:10:10PM +0300, Péter Ujfalusi wrote:
>>>> On 05/08/2026 12:00, Richard Fitzgerald wrote:
>>>>>>> Found by an audit of all reg_defaults tables under sound/, the
>>>>>>> SoundWire
>>>>>>> codec drivers are fixed by a separate series.
>>>>>>
>>>>>> Wow. Would it make sense to have a regmap helper to double-check the
>>>>>> addresses are indeed in-order in those reg_default tables?
>>>>>> I am not sure how this requirement can be enforced by just
>>>>>> inspection, a
>>>>>> warning would help detect this sort of issues on more platforms.
>>>>>>
>>>>> It does seem probable that anything that relies on people just
>>>>> remembering to keep a large table sorted is prone to breaking,
>>>>> especially if the addresses are provided by named constant instead of
>>>>> a list of hardcoded numbers.
>>>>>
>>>>> Should regmap check the table when the regmap is first created?
>>>>> As it has to search the table during normal use anyway, one extra walk
>>>>> when the regmap is created probably isn't a serious overhead.
>>>>
>>>> But it will be done for _all_ devices which uses regmap on boot, small
>>>> things do add up, see my reply to Pierre-Louis.
>>>
>>> Indeed, if we were to add some sort of auto-checker it should
>>> be guarded behind something like perhaps a Kconfig option or the
>>> DEBUG define.
>>>
>>> Thanks,
>>> Charles
>>
>> regcache_init() already walks the defaults table checking the stride
>>
>>      for (i = 0; i < config->num_reg_defaults; i++)
>>          if (config->reg_defaults[i].reg % map->reg_stride)
>>              return -EINVAL;
>>
>> so checking that each entry is larger than previous is trivial extra
>> overhead. I think most regmaps are cached.
> 
> Right, I think this should work:
> 
> diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
> index aa8f2efed779..ce4b11d8a758 100644
> --- a/drivers/base/regmap/regcache.c
> +++ b/drivers/base/regmap/regcache.c
> @@ -123,6 +123,7 @@ static void regcache_hw_exit(struct regmap *map)
>   
>   int regcache_init(struct regmap *map, const struct regmap_config *config)
>   {
> +	bool sort_defaults = false;
>   	int count = 0;
>   	int ret;
>   	int i;
> @@ -149,10 +150,15 @@ int regcache_init(struct regmap *map, const struct regmap_config *config)
>   		return -EINVAL;
>   	}
>   
> -	for (i = 0; i < config->num_reg_defaults; i++)
> +	for (i = 0; i < config->num_reg_defaults; i++) {
>   		if (config->reg_defaults[i].reg % map->reg_stride)
>   			return -EINVAL;
>   
> +		if (i && config->reg_defaults[i - 1].reg >

You could test the stride of defaults[0] first before the loop, and
start the loop at i = 1. Then on each loop you can test [i] against
[i - 1] without the need to check i != 0 every time.

I don't think we need to sort them. Just fail, so that an unsorted table
must be fixed.