linux-kernel - Re: [PATCH 4/4] ASoC: simple-card: Support for selecting system clocks by ID

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Date:	Tue, 16 Feb 2016 13:42:33 +0000
From:	Mark Brown <broonie@...nel.org>
To:	Peter Ujfalusi <peter.ujfalusi@...com>
Cc:	Michael Turquette <mturquette@...libre.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Liam Girdwood <lgirdwood@...il.com>,
	alsa-devel@...a-project.org, Jyri Sarha <jsarha@...com>,
	linux-clk@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Kristo, Tero" <t-kristo@...com>
Subject: Re: [PATCH 4/4] ASoC: simple-card: Support for selecting system
 clocks by ID

On Tue, Feb 16, 2016 at 11:46:52AM +0200, Peter Ujfalusi wrote:

> As for codecs, tlv320aic3106 is also pretty simple device from the outside, it
> can receive it's reference clock via:
> MCLK pin, GPIO2 pin or it can use the BCLK from the bus. Based on the incoming
> frequency it can use it directly or it needs to use the internal PLL to
> generate the cocks.
> It can output generated clock via GPIO1

That already sounds like there is room for configuration and hooking
into a wider clock tree - we've got three different source options and
an output plus a PLL that can presumably take in non-audio rates.

> I don't think it will bring any clarity or features we miss right now if we
> try to move CPU and codec drivers to clk API. IMHO.

You happen to be looking at a particularly simple system but things do
scale up and there's not a clear cutoff point which would allow us to
make a clear distinction between things that might get used in a simple
system and things that might need something more complex.  This seems
particularly important when we're adding things to simple-card, we want
it to be usable with as many different devices as possible.

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