linux-kernel - Re: [PATCH v2 3/3] regulator: axp20x: Fix axp22x ldo

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Message-ID: <20160427154819.GY3217@sirena.org.uk>
Date:	Wed, 27 Apr 2016 16:48:19 +0100
From:	Mark Brown <broonie@...nel.org>
To:	Hans de Goede <hdegoede@...hat.com>
Cc:	Liam Girdwood <lgirdwood@...il.com>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Chen-Yu Tsai <wens@...e.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] regulator: axp20x: Fix axp22x ldo_io registration
 error on cold boot

On Wed, Apr 27, 2016 at 05:35:31PM +0200, Hans de Goede wrote:
> On 27-04-16 17:12, Mark Brown wrote:

> >Why not just implement that?

> Given the formula in the datasheet to calculate the ldo_io
> regulator voltage 0x1f maps to 3.8V, but according to the
> datasheet the maximum voltage supported is 3.3V, iow the
> power-on-reset value of this register is out of spec
> according to the datasheet.

Well, I guess someone can just measure what happens?

> >We know what it does and it preserves the
> >expected behaviour where we don't touch the regualtor unless explicitly
> >told it's OK.  We'll only ever try to set that value if the machine
> >explicitly gives permission for it.

> The problem is that if we do not fix the out of spec
> register value then _regulator_get_voltage returns
> -EINVAL because the register value exceeds n_voltages

This will no longer be the case when the driver understands what the
startup value means.

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