linux-kernel - Re: [PATCH] regulator: twl: Add 'fixed' set

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Message-ID: <BANLkTi=pWMmfH+GV_kwm8_MtjPpsdNWD6w@mail.gmail.com>
Date:	Fri, 24 Jun 2011 18:36:10 +0530
From:	Jaswinder Singh <jaswinder.singh@...aro.org>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Cc:	Jassi Brar <jassisinghbrar@...il.com>,
	linux-kernel@...r.kernel.org, ti@...ts.linaro.org,
	linux-omap@...r.kernel.org, lrg@...com, sameo@...ux.intel.com
Subject: Re: [PATCH] regulator: twl: Add 'fixed' set_voltage callback

On 24 June 2011 16:49, Mark Brown <broonie@...nsource.wolfsonmicro.com> wrote:
> On Fri, Jun 24, 2011 at 02:16:54AM +0530, Jassi Brar wrote:
>> Define dummy set_voltage callback for fixed lines,
>> without which voltage constraints fail to apply.
>>
>> Signed-off-by: Jassi Brar <jaswinder.singh@...aro.org>
>
> No, this isn't sensible - fixed voltage regulators aren't an unusual
> property of this device, they've very common.  The core should handle
> this gracefully.  Probably whatever consumer is doing the setting also
> ought to be updated to check that the voltages it wants to set are
> supported at startup since

Well, there's no consumer in the picture yet. The core even fails to register
the regulator.
After digging deeper, I realized removing
       .apply_uV = true;
from the constraints is the correct solution. Patch is coming next.

> otherwise it can end up repeatedly trying to
> set something that'll never work.
Though the semantic could be defined that the 'closest' possible value
is already
set after the set_{voltage,current_limit} returns.
The consumer has no point in retrying - just like sample-rate setting
in Alsa works.

Thanks,
Jassi

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