Re: [PATCH v1 2/4] ASoC: codecs: Add FourSemi FS2104/5S audio amplifier driver

[Mark Brown <broonie@kernel.org>]

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On Mon, Jul 07, 2025 at 04:34:03PM +0800, Nick Li wrote:
> On Fri, Jul 04, 2025 at 03:37:32PM +0100, Mark Brown wrote:
> > On Fri, Jul 04, 2025 at 07:12:47PM +0800, Nick Li wrote:
> > > On Thu, Jul 03, 2025 at 03:59:34PM +0100, Mark Brown wrote:
> > > > On Thu, Jul 03, 2025 at 11:56:37AM +0800, Nick wrote:

> > > the volume will be masked in fs210x->vol[2],
> > > we restore the volume when the driver resumes(reinitializes) the deivce.

> > You're not just restoring the values on resume, you're also overwriting
> > them on probe.

> Yes, the volume will be set to the default value at the first time of initialization on probe,
> and it may be updated by volume control later.
> It's a good way to use the regmap cache(REGCACHE_RBTREE) to cache the volumes.

Great.  Note that for new things you should generally use _MAPLE
instead, it's a more modern data structure - _RBTREE can still make
sense for some specialist use cases but this is unlikely to be one of
them.

> > There's not great options here, and you're going to loose the start of
> > playback especially with devices that don't start clocking until audio
> > starts.  You really need the CPU vendors you're working with to
> > implement SND_SOC_DAIFMT_CONT or expose their clocks via the clock API
> > but not all hardware is able to do this.  I think given how limited your
> > hardware is here you really need something in trigger() or some new
> > callback that runs later than that, the delayed work you've got there is
> > trying to fudge things to run after trigger.

> We will start the start_work in dai->trigger if there is no clock bclk
> for us to control, and disable fading in/out in firmware to reduce
> the time consumption if it is needed(As a backup plan).

Great.  You could also make the fade in/out user selectable so the
application can trade off between pops/clicks and cut off audio.

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