linux-kernel - Re: [PATCH 4/6] regulator: Add operation to let drivers select vsel register

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Date:   Thu, 16 Feb 2023 10:05:49 +0100
From:   Frieder Schrempf <frieder.schrempf@...tron.de>
To:     Mark Brown <broonie@...nel.org>, Frieder Schrempf <frieder@...s.de>
Cc:     Liam Girdwood <lgirdwood@...il.com>, linux-kernel@...r.kernel.org,
        Marek Vasut <marex@...x.de>,
        ChiYuan Huang <cy_huang@...htek.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>
Subject: Re: [PATCH 4/6] regulator: Add operation to let drivers select vsel
 register

Hi Mark,

On 14.02.23 22:06, Mark Brown wrote:
> On Mon, Feb 13, 2023 at 04:58:22PM +0100, Frieder Schrempf wrote:
>> From: Frieder Schrempf <frieder.schrempf@...tron.de>
>>
>> There are regulators that use multiple registers for storing the
>> voltage. Add a get_reg_voltage_sel member to struct regulator_ops in
>> order to let drivers register a function that returns the currently
>> used register.
>>
>> The pca9450 driver will be a user of this as the LDO5 regulator of
>> that chip uses two different control registers depending on the
>> state of an external signal.
> 
> Aside from the build warnings the bots reported it's not clear to
> me that it's better to do this than it is to just have these
> drivers implement appropriate ops directly - there's probably
> going to be cases when it's a different bitfield in the same
> register, and by the time you've implemented the op so things
> aren't completely data driven I'm not sure how much you win by
> reusing the register read/write.

Thanks for the feedback. Makes sense to me, I can do that.

Just to be sure: you are suggesting to to leave the core untouched, use
the existing [get/set]_voltage() ops in the driver and reimplement the
logic of regulator_[get/set]_voltage_sel_regmap() there, right?

Thanks
Frieder