linux-kernel - Re: [PATCH 2/2] drm/panfrost: add devfreq regulator support

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Message-ID: <20200414185523.GO5412@sirena.org.uk>
Date:   Tue, 14 Apr 2020 19:55:23 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Clément Péron <peron.clem@...il.com>
Cc:     Steven Price <steven.price@....com>,
        Liam Girdwood <lgirdwood@...il.com>,
        Rob Herring <robh@...nel.org>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] drm/panfrost: add devfreq regulator support

On Tue, Apr 14, 2020 at 08:20:23PM +0200, Clément Péron wrote:
> Hi Liam and Mark,

You might want to flag stuff like this in the subject line, I very
nearly deleted this without opening it since most of the email I get
about panfrost appears to be coming from me having sent patches rather
than being relevant.

> We are having an issue with Panfrost driver registering two times the
> same regulator and giving an error when trying to create the debugfs
> folder.

> Could you clarify if it is allowed for a device to register two times
> the same regulator?

> I check Documentation/power/regulator/regulator.rst but this point is
> not specified.

We don't actively prevent it and I can't think what other than debugfs
might run into problems (and that's just a warning) but it does seem
like a weird thing to want to do and like it's pointing to some
confusion in your code with two different parts of the device
controlling the same supply independently.  What's the use case here?

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