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

From: Mark Brown
Date: Thu Feb 18 2016 - 19:27:35 EST


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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