Re: [PATCH v3 06/13] dt-bindings: reserved-memory: Wakeup Mailbox for Intel processors

Ricardo Neri
2025-05-13T22:09:48Z

On Mon, May 12, 2025 at 10:32:24AM -0500, Rob Herring wrote:
> On Tue, May 06, 2025 at 08:23:39PM -0700, Ricardo Neri wrote:
> > On Tue, May 06, 2025 at 09:10:22AM +0200, Krzysztof Kozlowski wrote:
> > > On Mon, May 05, 2025 at 10:16:10PM GMT, Ricardo Neri wrote:
> > > > > If this is a device, then compatibles specific to devices. You do not
> > > > > get different rules than all other bindings... or this does not have to
> > > > > be binding at all. Why standard reserved-memory does not work for here?
> > > > >
> > > > > Why do you need compatible in the first place?
> > > >
> > > > Are you suggesting something like this?
> > > >
> > > > reserved-memory {
> > > > # address-cells = <2>;
> > > > # size-cells = <1>;
> > > >
> > > > wakeup_mailbox: wakeupmb@fff000 {
> > > > reg = < 0x0 0xfff000 0x1000>
> > > > }
> > > >
> > > > and then reference to the reserved memory using the wakeup_mailbox
> > > > phandle?
> > >
> > > Yes just like every other, typical reserved memory block.
> >
> > Thanks! I will take this approach and drop this patch.
>
> If there is nothing else to this other than the reserved region, then
> don't do this. Keep it like you had. There's no need for 2 nodes.

Thank you for your feedback!

I was planning to use one reserved-memory node and inside of it a child
node to with a `reg` property to specify the location and size of the
mailbox. I would reference to that subnode from the kernel code.

IIUC, the reserved-memory node is only the container and the actual memory
regions are expressed as child nodes.

I had it like that before, but with a `compatible` property that I did not
need.

Am I missing anything?

Thanks and BR,
Ricardo