Re: [PATCH v15 2/4] ASoC: tac5xx2-sdw: add soundwire based codec driver

[Pierre-Louis Bossart <pierre-louis.bossart@linux.dev>]

On 5/4/26 15:52, Mark Brown wrote:
> On Mon, May 04, 2026 at 06:27:14PM +0530, Niranjan H Y wrote:
>> Add codec driver for tac5xx2 family of devices.
> 
>> +static s32 tac5xx2_sdca_dev_resume(struct device *dev)
>> +{
>> +	struct tac5xx2_prv *tac_dev = dev_get_drvdata(dev);
>> +	struct sdw_slave *slave = dev_to_sdw_dev(dev);
>> +	unsigned long t;
>> +	int ret;
> 
>> +
>> +	/* Detect and set jack type for UAJ path before playback.
>> +	 * This is required as jack detection does not trigger interrupt
>> +	 * when device is in runtime_pm suspend with bus in clock stop mode.
>> +	 */
>> +	if (tac_has_uaj_support(tac_dev))
>> +		tac5xx2_sdca_headset_detect(tac_dev);
>> +
>> +regmap_sync:
>> +	regcache_cache_only(tac_dev->regmap, false);
>> +	regcache_mark_dirty(tac_dev->regmap);
>> +	ret = regcache_sync(tac_dev->regmap);
>> +	if (ret < 0)
>> +		dev_warn(dev, "Failed to sync regcache: %d\n", ret);
> 
> We do the jack detect before we reinitialise the registers, meaning the
> device is still in cache only mode and volatile reads will all return
> -EBUSY.

Indeed, and there's also another set of initializations that won't happen in the io_init.

It's a bit complicated because we have to deal with device attachment and suspend-resume, and the two parts aren't necessarily equivalent.
- when resuming the bus the codec will also be resumed
- but the device can go to runtime_pm suspend while still attached on the bus (e.g. if another device is active on the same bus).

Other drivers have regcache_cache_only(tac_dev->regmap, false); in the two paths (io_init and resume) to make sure both cases are handled.