linux-kernel - Re: [PATCHv2 6/6] ASoC: da7213: Add default clock handling

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Date:   Tue, 26 Nov 2019 17:50:40 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Cc:     Sebastian Reichel <sebastian.reichel@...labora.com>,
        Support Opensource <Support.Opensource@...semi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "kernel@...labora.com" <kernel@...labora.com>
Subject: Re: [PATCHv2 6/6] ASoC: da7213: Add default clock handling

On Tue, Nov 26, 2019 at 05:39:45PM +0000, Adam Thomson wrote:
> On 26 November 2019 17:09, Mark Brown wrote:

> > If we're special casing simple-card we're doing it wrong - there's
> > nothing stopping any other machine driver behaving in the same way.

> Ok, what's being proposed here is for the codec to automatically control the PLL
> rather than leaving it to the machine driver as is the case right now. In the
> possible scenario where this is done using a card level widget to enable/disable

Wasn't the proposal to add a new mode where the machine driver *could*
choose to delgate PLL selection to the CODEC driver rather than do so
unconditionally?  

> the PLL we will conflict with that using the current suggested approach for the
> da7213 driver, albeit with no real consequence other than configuring the PLL
> twice the first time a stream is started. It's a case of how to determine who's
> in control of the PLL here; machine driver or codec?

The patch looked like the idea was that as soon as the machine driver
configures the PLL the CODEC driver will stop touching it which looked
like a reasonable way of doing it, you could also do it with an explicit
SYSCLK value (which would have to be 0 for generic machine drivers to
pick it up) but this works just as well and may even be better.  Perhaps
I misread it though.

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