Re: [PATCH 1/2] dt-bindings: mmc: mmc-pwrseq-simple: add support for reset control

[Marco Felsch]

On 24-10-07, Rob Herring wrote:
> On Mon, Oct 07, 2024 at 03:32:42PM +0000, POPESCU Catalin wrote:
> > On 05/10/2024 20:26, Rob Herring wrote:
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> > > On Fri, Oct 04, 2024 at 02:07:39PM +0200, Catalin Popescu wrote:
> > >> Add compatible value "mmc-pwrseq-simple-reset" to support reset control
> > >> instead of gpios. Reset controls being refcounted, they allow to use
> > >> shared resets or gpios across drivers. Support of reset control is
> > >> limited to one single reset control.
> > > Can't you do this without a binding change? Just use reset controls when
> > > there is only 1 GPIO.
> > 
> > That's a good question. The idea was to keep in place the gpio support 
> > w/o impacting any platform using pwrseq-simple.
> 
> Why would it matter? If not shared, then the behavior should be the 
> same. If shared, we want to maintain the broken behavior?

My two cents on this. This will break systems which haven't the
RESET_GPIO driver enabled yet. Therefore we may get regressions mails.
I'm fine with it if that is okay.

Regards,
  Marco

> > Also, later on when support for a list of reset gpios will be added to 
> > the reset framework, this would not work anymore...
> 
> Why not?
> 
> How an OS handles reset-gpios is up to the OS. It can evolve. The 
> binding can't evolve because it is an ABI.
> 
> Also, a list is kind of broken to begin with for a "generic" binding. 
> What's the order the lines should be asserted/deasserted? What about 
> timing requirements? You don't know because every device is different. 
> This binding would not be accepted now, so extending it is questionable.
> 
> Rob
>