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Date:   Tue, 30 Jul 2019 16:50:27 +0100
From:   Mark Brown <broonie@kernel.org>
To:     Thomas Preston <thomas.preston@codethink.co.uk>
Cc:     Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org,
        alsa-devel@alsa-project.org,
        Charles Keepax <ckeepax@opensource.cirrus.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
        Kirill Marinushkin <kmarinushkin@birdec.tech>,
        Cheng-Yi Chiang <cychiang@chromium.org>,
        Marco Felsch <m.felsch@pengutronix.de>,
        Takashi Iwai <tiwai@suse.com>,
        Annaliese McDermond <nh6z@nh6z.net>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Paul Cercueil <paul@crapouillou.net>,
        Vinod Koul <vkoul@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@linaro.org>,
        linux-kernel@vger.kernel.org, Jerome Brunet <jbrunet@baylibre.com>
Subject: Re: [alsa-devel] [PATCH v2 3/3] ASoC: TDA7802: Add turn-on
 diagnostic routine
Message-ID: <20190730155027.GJ4264@sirena.org.uk>
References: <20190730120937.16271-1-thomas.preston@codethink.co.uk>
 <20190730120937.16271-4-thomas.preston@codethink.co.uk>
 <20190730141935.GF4264@sirena.org.uk>
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On Tue, Jul 30, 2019 at 04:25:56PM +0100, Thomas Preston wrote:
> On 30/07/2019 15:19, Mark Brown wrote:

> > It is unclear what this mutex usefully protects, it only gets taken when
> > writing to the debugfs file to trigger this diagnostic mode but doesn't
> > do anything to control interactions with any other code path in the
> > driver.

> If another process reads the debugfs node "diagnostic" while the turn-on=
=20
> diagnostic mode is running, this mutex prevents the second process
> restarting the diagnostics.

> This is redundant if debugfs reads are atomic, but I don't think they are.

Like I say it's not just debugfs though, there's the standard driver
interface too.

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