Re: [PATCH 2/4] regulator: Add driver for MT6331 PMIC regulators

[AngeloGioacchino Del Regno]

Il 23/05/22 15:43, Mark Brown ha scritto:
> On Mon, May 23, 2022 at 03:22:39PM +0200, AngeloGioacchino Del Regno wrote:
> > Il 23/05/22 15:00, Mark Brown ha scritto:
>
> > > Right, my point here is that it looks awfully like the documentation
> > > (this came from documentation I guess?) is including some extra bits
> > > that get ignored in the voltage selection field here.  That seems like a
> > > weird choice somewhere along the line.
>
> > I wish I had a datasheet for these parts...
>
> > All of this comes from analyzing a running device on the downstream 3.4 kernel
> > and on understanding the (not really readable) downstream kernel code...
> > ..but yes, I agree on the fact that this seems to be a weird choice.
>
> > Ah, besides, I hooked up an oscilloscope to the VCAM_IO and I can see that the
> > vreg really does react as expected upon setting the upper bits.. but since it
> > still works without, we can safely ignore them, which makes us able to simplify
> > the driver (as no custom code for that will be required) and, at the same time,
> > avoid seeing a table of values repeated 4 times in a row.
>
> That seems safer in general if we don't know what those bits are doing -
> it could be some kind of mode control or something.
>
> > ...so, the regulator will indeed shut itself off and clear either/both the QI_EN
> > and/or its relative bit in the enable register... I've also just found hints of
> > the latter (enable register being set to 0) downstream, so I'm sure that this is
> > indeed right.
>
> That's still not quite the same thing as a status bit, if the regulator
> disables itself then it won't try to turn itself back on.  Note that the
> core will fall back on using the enable state if there's no status op so
> there's no need for this logic, you can just omit the status op and the
> behaviour will be the same.

Ok then, I'll simply remove that!

Thanks,
Angelo