Re: [PATCH v1 1/3] dt-bindings: mmc: rockchip-dw-mshc: add rockchip,disable-runtime-pm

["Heiko Stübner" <heiko@sntech.de>]

Hi Marco,

Am Montag, 12. Januar 2026, 00:51:24 Mitteleuropäische Normalzeit schrieb Marco Schirrmeister:
> On Sun, Jan 11, 2026 at 10:41 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> > > +  rockchip,disable-runtime-pm:
> > > +    type: boolean
> > > +    description:
> > > +      Inhibit runtime power management. This is required for boards
> >
> > What is runtime power management? Like Linux PM? If anything phrased
> > like that is it is a clear no go. Bindings describe hardware.
> 
> You are right. This refers to the Linux PM subsystem and describes
> software behavior.
> 
> > > +      where the bus timing becomes unstable if the controller is
> > > +      runtime-suspended.
> >
> > You described the desired Linux feature or behavior, not the actual
> > hardware. The bindings are about the latter, so instead you need to
> > rephrase the property and its description to match actual hardware
> > capabilities/features/configuration etc.
> 
> On this board, the bus timing becomes unstable when waking up from
> a low-power state. This causes a constant retraining loop.

As you describe it here, it does sound like a real hardware quirk (which
would be a dt-thing) ... it's just that the previous wording describes it
in a non-hardware way - as Krzysztof pointed out in his reply.


> I will move this logic into the driver and handle it as a board specific
> quirk using of_machine_is_compatible("friendlyarm,nanopi-r76s")
> instead. I will send a v2.

This won't fly I think. We can't really have a (possibly long) list of

If (boardA) foo();
if (boardB) bar();
if (boardC) bas();

That really is not sustainable and most likely won't get accepted.

Heiko