linux-kernel - Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock

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Message-ID: <6ed28bb5330879b1919aced5174f319f@walle.cc>
Date:   Fri, 12 Mar 2021 13:01:41 +0100
From:   Michael Walle <michael@...le.cc>
To:     Mark Brown <broonie@...nel.org>
Cc:     Sameer Pujar <spujar@...dia.com>, alsa-devel@...a-project.org,
        devicetree@...r.kernel.org, jonathanh@...dia.com,
        kuninori.morimoto.gx@...esas.com, linux-kernel@...r.kernel.org,
        linux-tegra@...r.kernel.org, robh@...nel.org, sharadg@...dia.com,
        thierry.reding@...il.com
Subject: Re: [PATCH 1/3] ASoC: simple-card-utils: Fix device module clock

Am 2021-03-12 12:35, schrieb Mark Brown:
> On Thu, Mar 11, 2021 at 11:11:15PM +0100, Michael Walle wrote:
>> Am 2021-03-11 17:15, schrieb Mark Brown:
> 
>> > The trick is figuring out if it's best to vary the input clock
>> > or to use the FLL to adapt a fixed input clock,
> 
>> For simple-audio-card you can set the "clock" property if you want
>> that clock to be changed/enabled/disabled. But that doesn't seem to
>> be the way to go, at least it was NAKed by Rob for the 
>> audio-graph-card.
>> I don't see a way to figure out if MCLK should be controlled by
>> simple-*-card without adding further properties to the device tree.
> 
> If the card has a clock API clock as sysclk then set_sysclk(() should
> be configuring that clock.

What do you mean by "the card". The simple-audio-card itself?

Take a look at:
https://elixir.bootlin.com/linux/v5.12-rc2/source/arch/arm64/boot/dts/freescale/fsl-ls1028a-kontron-sl28-var3-ads2.dts#L29

Does the card has a clock? IMHO the WM8904 codec has a clock, but not
the audio card.

-michael