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

From: Waldemar Rymarkiewicz
Date: Tue Jul 04 2017 - 06:58:51 EST

Hi Mark,

On 3 July 2017 at 17:36, Mark Brown <broonie@xxxxxxxxxx> wrote:
> On Mon, Jul 03, 2017 at 05:33:03PM +0200, Waldemar Rymarkiewicz wrote:
>> I've asked also on TI forum if this is typical to the regulator not to
>> determine the startup voltage but still waiting for feedback. Anyway,
>> if this is the case I guess a driver is a good place to update
>> register before we register to the regulator framework.
> It's really unusual to have a device that has the voltage changable by
> register write at runtime where the current state can't be read back.

or you did not realise that this is initialised by bootloader for example.

After investigating this issue a bit more I've found that this is
rather typical for power regulators not to update a register with
startup voltage set by a feedback resistor divider as it would cost
extra circuit. So, I assume that most likely a bootloader normally
initializes power regulator in case it's needed eg. if it's supplying
CPU which is DVS-enabled.

Anyway, it's more clear now to me how this should be done.