linux-kernel - Re: [PATCH] ASoC: adau1761: Reset codec at probe and shutdown

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Date:   Mon, 8 Aug 2022 12:54:22 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Niklas Carlsson <Niklas.Carlsson@...s.com>
Cc:     Lars-Peter Clausen <lars@...afoo.de>,
        Nuno Sá <nuno.sa@...log.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Niklas Carlsson <niklasc@...s.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ASoC: adau1761: Reset codec at probe and shutdown

On Sat, Aug 06, 2022 at 12:21:20AM +0200, Niklas Carlsson wrote:

> +	 * Steps for performing the reset:
> +	 *   1) Make sure that the cache is marked as dirty by writing all
> +	 *      default values directly to the cache.

Why?  If there's some need to mark the cache as dirty there's a function
that directly does that.  Note especially that a cache sync will
explicitly not write any default values to the hardware if it knows
about them.

> +	 *   2) Enable the core clock which is needed for writing all registers
> +	 *      except CLOCK_CONTROL.
> +	 *
> +	 *   3) Use regcache_sync() for synchronizing the dirty cache back to
> +	 *      the hardware.

We then need to disable clock control at the end (which the code does
but the comment doesn't).  It might be better to just have comments next
to the individual steps here.

I'd expect something more like

	enable clock
	for each register except CLOCK_CONTROL write the default
	disable clock

here, no faffing with the cache.  You could use two bulk writes to do
the writes of registers below and above CLOCK_CONTROL if that's the goal
in doing a cache sync.

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