linux-kernel - Re: [PATCH v2] ASoC: da7219: read fmw property to get mclk for non-dts systems

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Message-ID: <20180501205006.GE2714@sirena.org.uk>
Date:   Wed, 2 May 2018 05:50:06 +0900
From:   Mark Brown <broonie@...nel.org>
To:     Adam Thomson <Adam.Thomson.Opensource@...semi.com>
Cc:     Akshu Agrawal <akshu.agrawal@....com>,
        "djkurtz@...omium.org" <djkurtz@...omium.org>,
        "Alexander.Deucher@....com" <Alexander.Deucher@....com>,
        Support Opensource <Support.Opensource@...semi.com>,
        Jaroslav Kysela <perex@...ex.cz>,
        Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        "moderated list:SOUND" <alsa-devel@...a-project.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] ASoC: da7219: read fmw property to get mclk for
 non-dts systems

On Mon, Apr 30, 2018 at 07:05:19PM +0000, Adam Thomson wrote:

> There is already a means via DT to specify the MCLK for a device using the
> generic clock DT bindings, and this driver already uses that. Should ACPI not
> have something similar to that which is generic, rather than adding device
> specific bindings/properties to achieve the same? There will be other drivers
> that will want to do the same.

There's a lot of things that ACPI *should* do but doesn't - it's a bit
of a shambles how ACPI standards get defined and what's there is not
really intended to handle systems like these semi-embedded ones.  One of
the big gaps in ACPI is that it has no handling at all of clocks, that's
supposed to be done transparently by firmware in the ACPI model.  What a
lot of the embedded Intel people have been doing is coopting the DT
bindings wholesale for ACPI systems but that has problems when you get
into areas which should be handled in some way on ACPI systems like
power and unfortunately clocks are kind of power adjacent so might be a
bit sketchy here.

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