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From: Francesco Dolcini <francesco@dolcini.it>
To: Mark Brown <broonie@kernel.org>
Cc: linux-kernel@vger.kernel.org, Liam Girdwood <lgirdwood@gmail.com>
Subject: Re: fixed-regulator with enable from another regulator
Date: Sat, 28 Jan 2023 14:43:23 +0100	[thread overview]
Message-ID: <C1E878D9-2C30-454A-AC4D-DB2996313544@dolcini.it> (raw)
In-Reply-To: <Y9UgENl4KZT5e/ot@sirena.org.uk>

Il 28 gennaio 2023 14:16:00 CET, Mark Brown <broonie@kernel.org> ha scritto:
>On Fri, Jan 27, 2023 at 10:33:14PM +0100, Francesco Dolcini wrote:
>
>> I am trying to figure out if it is possible with the current
>> regulator-fixed or with any other solution already implemented in Linux
>> to have a regulator enabled from another one.
>
>Not really.  You can model the regulators as sharing the same
>enable if there's a GPIO enable for the parent regulator,
>otherwise it'd need some framework work.

Thanks, I'll propose a patch if needed.

>> I am still not 100% sure if describing this specific hardware connection
>> would be required on my system, maybe I can just ignore all of that.
>
>It seems like a fairly strange hardware design TBH.

Just to shred some light on this weird request, I am not the one who did the design, but there is a reason.

There is one device that requires 3 different voltages, one of those come from a dedicated output of a PMIC, the other 2 from dedicated LDOs.

Having the enable of the 2 LDO on the PMIC output allows to control the power of the device without additional GPIOs usage (that were not available, for instance, while the PMIC can enable/disable the output from I2C).

(not that is relevant for this discussion, but this is of course fine for the power sequencing of this specific device).

Francesco


Hello Mark,

      reply	other threads:[~2023-01-28 13:43 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-27 21:33 fixed-regulator with enable from another regulator Francesco Dolcini
2023-01-28 13:16 ` Mark Brown
2023-01-28 13:43   ` Francesco Dolcini [this message]

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