Re: [PATCH 18/18] ipu3: Add driver for dummy INT3472 ACPI device

[Andy Shevchenko]

On Wed, Dec 02, 2020 at 02:42:28PM +0200, Laurent Pinchart wrote:
> On Wed, Dec 02, 2020 at 01:09:56PM +0200, Sakari Ailus wrote:
> > On Tue, Dec 01, 2020 at 08:37:58PM +0200, Laurent Pinchart wrote:

...

> I think we should consider ACPI to be a hack in the first place :-)

I feel that about DT (and all chaos around it) but it's not a topic here.

> > Could this be just one more platform device for each of the three cases (or
> > one for the two latter; I'm not quite sure yet)?
> 
> Using MFD for this seems a bit overkill to me. I won't care much as I
> won't maintain those drivers, but the current situation is complex
> enough, it was hard for me to understand how things worked. Adding yet
> another layer with another platform device won't make it any simpler.
> 
> If we want to split this in two, I'd rather have a tps68470 driver on
> one side, without ACPI op region support, but registering regulators,
> GPIOs and clocks (without using separate drivers and devices for these
> three features), and an INT3472 driver on the other side, with all the
> ACPI glue and hacks. The tps68470 code could possibly even be structured
> in such a way that it would be used as a library by the INT3472 driver
> instead of requiring a separate platform device.

I'm afraid TPS68470 is MFD in hardware and its representation in the MFD is
fine. What we need is to move IN3472 pieces out from it.

And I agree with your proposal in general.

> > The GPIO regulator case is relatively safe, but the real PMICs require
> > regulator voltage control as well as enabling and disabling the regulators.
> > That probably requires either schematics or checking the register values at
> > runtime on Windows (i.e. finding out which system you're dealing with, at
> > runtime).

-- 
With Best Regards,
Andy Shevchenko