linux-kernel - Re: [RFC PATCH 1/2] Regulator: Core: Add clock-enable to fixed-regulator

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Message-ID: <20190806182606.GG4527@sirena.org.uk>
Date:   Tue, 6 Aug 2019 19:26:06 +0100
From:   Mark Brown <broonie@...nel.org>
To:     Philippe Schenker <philippe.schenker@...adex.com>
Cc:     "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH 1/2] Regulator: Core: Add clock-enable to
 fixed-regulator

On Tue, Aug 06, 2019 at 12:57:32PM +0000, Philippe Schenker wrote:
> On Mon, 2019-08-05 at 17:37 +0100, Mark Brown wrote:

> > So the capacitor on the input of the p-FET is keeping the switch on?
> > When I say it's not switching with the clock I mean it's not constantly
> > bouncing on and off at whatever rate the clock is going at.

> Ah, that's what you mean. Yes, the capacitor gets slowly charged with
> the
> resistor but nearly instantly discharged with the n-FET. So this
> capacitor
> is used as a Low-Pass filter to get the p-FET to be constantly switched.

> It is not bouncing on and off with the clock but rather it is switched
> constantly.

Good, I guess this might be part of why it's got this poor ramp time.

> > I think you are going to end up with a hack no matter what.

> That's exactly what I'm trying to prevent. To introduce a fixed
> regulator that can have a clock is not a hack for me.
> That the hardware solution is a hack is debatable yes, but why should I
> not try to solve it properly in software?

A lot of this discussion is around the definition of terms like "hack"
and "proper".

> In the end I just want to represent our hardware in software. Would you
> agree to create a new clock-regulator.c driver?
> Or would it make more sense to extend fixed.c to support clocks-enable
> without touching core?

At least a separate compatible makes sense, I'd have to see the code to
be clear if a completely separate driver makes sense but it'll need
separate ops at least.  There'd definitely be a lot of overlap though so
it's worth looking at.

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