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

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Message-ID: <20170703151133.su3uqfyimtl5vzvs@sirena.org.uk>
Date:   Mon, 3 Jul 2017 16:11:33 +0100
From:   Mark Brown <broonie@...nel.org>
To:     "Bartholomae, Thomas" <t.bartholomae@...el.com>
Cc:     Waldemar Rymarkiewicz <waldemar.rymarkiewicz@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Liam Girdwood <lgirdwood@...il.com>
Subject: Re: Where to update regulator register with initial voltage set by HW

On Fri, Jun 30, 2017 at 12:26:52PM +0000, Bartholomae, Thomas wrote:
> Hi Mark,

Please don't top post, reply in line with needed context.  This allows
readers to readily follow the flow of conversation and understand what
you are talking about and also helps ensure that everything in the
discussion is being addressed.

Please fix your mail client to word wrap within paragraphs at something
substantially less than 80 columns.  Doing this makes your messages much
easier to read and reply to.

> The problem is that our used regulator TPS65273V from TI do not have
> the possibility to read the current voltage defined by the HW, means
> by the circuit of the regulator.  In this case the register holding
> the voltage to be set later by software has a reset value which is
> normally the min value the regulator can support. This value can be
> out of the range of the supported rail. Therefore before the regulator
> gets registered this register needs to be set with a 'good' value.  I
> assume the only practicable solution will be that we initialize this
> voltage register in the boot code where we also set the CPU frequency.

You probably need platform data to tell the kernelw hat teh startup
value is.

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