linux-kernel - Re: [alsa-devel] [PATCH v2 2/3] ASoC: Add codec driver for ST TDA7802

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Message-ID: <820e2ea9-14a2-795c-9b78-e8f2a30afdb1@codethink.co.uk>
Date:   Wed, 31 Jul 2019 09:57:12 +0100
From:   Thomas Preston <thomas.preston@...ethink.co.uk>
To:     Marco Felsch <m.felsch@...gutronix.de>
Cc:     Mark Rutland <mark.rutland@....com>, devicetree@...r.kernel.org,
        alsa-devel@...a-project.org,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Kuninori Morimoto <kuninori.morimoto.gx@...esas.com>,
        Kirill Marinushkin <kmarinushkin@...dec.tech>,
        linux-kernel@...r.kernel.org, Takashi Iwai <tiwai@...e.com>,
        Annaliese McDermond <nh6z@...z.net>,
        Liam Girdwood <lgirdwood@...il.com>,
        Paul Cercueil <paul@...pouillou.net>,
        Rob Herring <robh+dt@...nel.org>,
        Vinod Koul <vkoul@...nel.org>, Mark Brown <broonie@...nel.org>,
        Srinivas Kandagatla <srinivas.kandagatla@...aro.org>,
        Patrick Glaser <pglaser@...la.com>,
        Rob Duncan <rduncan@...la.com>,
        Jerome Brunet <jbrunet@...libre.com>,
        Nate Case <ncase@...la.com>,
        Cheng-Yi Chiang <cychiang@...omium.org>
Subject: Re: [alsa-devel] [PATCH v2 2/3] ASoC: Add codec driver for ST TDA7802

On 31/07/2019 07:06, Marco Felsch wrote:
> Hi Thomas,
> 
> again sorry for jumping in..
> 

Np!

> On 19-07-30 18:26, Thomas Preston wrote:
>> On 30/07/2019 15:58, Mark Brown wrote:
>>> On Tue, Jul 30, 2019 at 01:09:36PM +0100, Thomas Preston wrote:
>>>> +	case SND_SOC_BIAS_STANDBY:
>>>> +		err = regulator_enable(tda7802->enable_reg);
>>>> +		if (err < 0) {
>>>> +			dev_err(component->dev, "Could not enable.\n");
>>>> +			return err;
>>>> +		}
>>>> +		dev_dbg(component->dev, "Regulator enabled\n");
>>>> +		msleep(ENABLE_DELAY_MS);
>>>
>>> Is this delay needed by the device or is it for the regulator to ramp?
>>> If it's for the regulator to ramp then the regulator should be doing it.
>>>
>>
>> According to the datasheet the device itself takes 10ms to rise from 0V
>> after PLLen is enabled. There are additional rise times but they are
>> negligible with default capacitor configuration (which we have).
>>
>> Good to know about the regulator rising configuration though. Thanks.
> 
> Isn't it the regulator we mentioned to not use that because it is a
> GPIO?
> 

Yeah it is - I intend to switch PLLen to gpio API.