linux-kernel - Re: [PATCH 2/3] drivers: regulator: qcom: add PMS405 SPMI regulator

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Message-ID: <20190427182113.GL14916@sirena.org.uk>
Date:   Sun, 28 Apr 2019 03:21:13 +0900
From:   Mark Brown <broonie@...nel.org>
To:     Jorge Ramirez <jorge.ramirez-ortiz@...aro.org>
Cc:     lgirdwood@...il.com, robh+dt@...nel.org, mark.rutland@....com,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org,
        bjorn.andersson@...aro.org, vinod.koul@...aro.org,
        niklas.cassel@...aro.org, khasim.mohammed@...aro.org,
        linux-arm-kernel@...ts.infradead.org, linux-arm-msm@...r.kernel.org
Subject: Re: [PATCH 2/3] drivers: regulator: qcom: add PMS405 SPMI regulator

On Thu, Apr 25, 2019 at 09:44:00PM +0200, Jorge Ramirez wrote:

> the way I see it, if I follow your suggestion and since we are not
> allowed to extend spmi_regulator_find_range(), the only options are:

> 1) duplicate verbatim this whole function
> (spmi_regulator_select_voltage_same_range) with a minor change (this
> amount of code duplication in the kernel seems rather unnecessary to me)

> 2) modify the struct spmi_regulator definition with a new operation that
> calls a different implementation of find range (seems a massive overkill)

Since the point of this change is AFAICT that this regulator only has a
single linear range it seems like it should just be able to use the
existing generic functions shouldn't it?  It just needs it's own
set/get_voltage_sel() operations.  As far as I can see the main thing
the driver is doing with the custom stuff is handling the fact that
there's multiple ranges but that's not an issue for this regulator.
It's possible I'm missing something there but that was the main thing
(and we do have some generic support for multiple linear ranges in the
helper code already, can't remember why this driver isn't using that -
the ranges overlap IIRC?).

TBH looking at the uses of find_range() I'm not sure they're 100%
sensible as they are - the existing _time_sel() is assuming we only need
to work out the ramp time between voltages in the same range which is
going to have trouble.

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