linux-kernel - Re: Where to update regulator register with initial voltage set by HW

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Message-ID: <CAHKzcEP7X1aodw+mcvrXKsK9qaGc=Oj6O8CrrjDo2RSTF_mpPw@mail.gmail.com>
Date:   Fri, 30 Jun 2017 13:37:32 +0200
From:   Waldemar Rymarkiewicz <waldemar.rymarkiewicz@...il.com>
To:     Mark Brown <broonie@...nel.org>
Cc:     linux-kernel@...r.kernel.org, Liam Girdwood <lgirdwood@...il.com>,
        "Bartholomae, Thomas" <t.bartholomae@...el.com>
Subject: Re: Where to update regulator register with initial voltage set by HW

On 30 June 2017 at 12:41, Mark Brown <broonie@...nel.org> wrote:
> On Thu, Jun 29, 2017 at 09:18:09AM +0200, Waldemar Rymarkiewicz wrote:
>
>> Initially, on boot, the voltage is set by HW (sensing resistors). When
>> OS starts and the reg driver registers regulator with the specific
>> constraints uV_min and uV_max, regulator core will apply uV_min or
>> uV_max if current (in regulator register) setting is not in the range.
>> Normally, by default register holds min(voltage_table) which is
>> different than the value set by HW (sensing resistors).
>
> You shoudn't be specfiying a default value for the register, clearly
> there is none as it is determined dynamically by the hardware when the
> system boots.

Thanks Mark for your feedback.

I am not sure if I understand. Do you mean, a regulator should
determine a voltage and update a register with a right selector when
system boots, so the regulator framework reading reg register knows
actual voltage?

BTW, I work with TPS65273 regulator.

/Waldek