From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mark Brown <broonie@kernel.org>
Subject: Re: [alsa-devel] [PATCH v2 3/3] ASoC: TDA7802: Add turn-on
 diagnostic routine
Date: Fri, 2 Aug 2019 12:10:36 +0100
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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>, Liam Girdwood <lgirdwood@gmail.com>, Marco Felsch <m.felsch@pengutronix.de>, Annaliese McDermond <nh6z@nh6z.net>, Takashi Iwai <tiwai@suse.com>, Paul Cercueil <paul@crapouillou.net>, Vinod Koul <vkoul@kernel.org>, Rob Herring <robh+dt@kernel.org>, Srinivas Kandagatla <srinivas.kandagatla@linaro.org>, Jerome Brunet <jbrunet@baylibre.com>, linux-kernel@vger.kernel.org, Cheng-Yi Chiang <cychiang@chromium.org>
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On Fri, Aug 02, 2019 at 09:32:17AM +0100, Thomas Preston wrote:
> On 02/08/2019 00:42, Mark Brown wrote:

> > Yes, that's definitely doable - we've got some other drivers with
> > similar things like calibration triggers exposed that way.

> One problem with using a kcontrol as a trigger for the turn-on diagnostic
> is that the diagnostic routine has a "return value".

You can use a read only control for the readback, or just have it be
triggered by overwriting the readback value.  You can cache the result.

> Hm, maybe a better idea is to have the turn on diagnostic only run on
> device probe (as its name suggests!), and print something to dmesg:

> 	modprobe tda7802 turn_on_diagnostic=1

> 	tda7802-codec i2c-TDA7802:00: Turn on diagnostic 04 04 04 04

> Kirill Marinushkin mentioned this in the first review [0], it just didn't
> really sink in until now!

You could do that too, yeah.  Depends on what this is diagnosing and if
that'd be useful.

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