From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Preston Subject: Re: [alsa-devel] [PATCH v2 3/3] ASoC: TDA7802: Add turn-on diagnostic routine Date: Fri, 2 Aug 2019 15:51:09 +0100 Message-ID: References: <20190730120937.16271-1-thomas.preston@codethink.co.uk> <20190730120937.16271-4-thomas.preston@codethink.co.uk> <20190730141935.GF4264@sirena.org.uk> <45156592-a90f-b4f8-4d30-9631c03f1280@codethink.co.uk> <20190730155027.GJ4264@sirena.org.uk> <9b47a360-3b62-b968-b8d5-8639dc4b468d@codethink.co.uk> <20190801234241.GG5488@sirena.org.uk> <472cc4ee-2e80-8b08-d842-79c65df572f3@codethink.co.uk> <20190802111036.GB5387@sirena.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190802111036.GB5387@sirena.org.uk> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Mark Brown Cc: Mark Rutland , devicetree@vger.kernel.org, alsa-devel@alsa-project.org, Charles Keepax , Kuninori Morimoto , Kirill Marinushkin , Liam Girdwood , Marco Felsch , Annaliese McDermond , Takashi Iwai , Paul Cercueil , Vinod Koul , Rob Herring , Srinivas Kandagatla , Jerome Brunet , linux-kernel@vger.kernel.org, Cheng-Yi Chiang List-Id: devicetree@vger.kernel.org On 02/08/2019 12:10, Mark Brown wrote: > 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. > Keeping the trigger and result together like that would be better I think, although the routine isn't supposed to run mid way through playback. If we're mid playback the debugfs routine has to turn off AMP_ON, take the device back to a known state, run diagnostics, then restore. Which causes a gap in the audible sound. >> 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. > The diagnostic status bits describe situations such as: - open load (no speaker connected) - short to GND - short to VCC - etc The intention is to test if all the speakers are connected. So, one might have a self test which runs the diagnostic and verifies it outputs: 00 00 00 00 For example, on my test rig there is only one speaker connected. So it reads: 04 04 00 04 Where the second bit is "open load". So this would fail the test. So in the kcontrol case the test would be something like: amixer sset "AMP1 turn on diagnostic" on amixer sget "AMP1 diagnostic" And the module parameter case: rmmod tda7802 modprobe tda7802 turn_on_diagnostic=1 dmesg | grep "Turn on diagnostic 04 04 04 04" rmmod tda7802 modprobe tda7802 I think the module parameter method is more appropriate for a "Turn-on diagnostic", even though I don't really like grepping dmesg for the result. I'll go ahead and implement that unless anyone has a particular preference for the kcontrol-trigger. Thanks