On Wed, May 14, 2025 at 10:42:48AM -0500, Rob Herring wrote:

On Tue, May 13, 2025 at 03:14:56PM -0700, Ricardo Neri wrote:

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On Mon, May 12, 2025 at 10:32:24AM -0500, Rob Herring wrote:

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On Tue, May 06, 2025 at 08:23:39PM -0700, Ricardo Neri wrote:

quoted

On Tue, May 06, 2025 at 09:10:22AM +0200, Krzysztof Kozlowski wrote:

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On Mon, May 05, 2025 at 10:16:10PM GMT, Ricardo Neri wrote:

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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?

Without a compatible, how do you identify which reserved region is the 
wakeup mailbox?

I thought using a phandle to the wakeup_mailbox. Then I realized that the
device nodes using the mailbox would be CPUs. They would need a `memory-
region` property. This does not look right to me.

Before you say node name, those are supposed to be 
generic though we failed to enforce anything for /reserved-memory child 
nodes.

I see. Thanks for preventing me from doing this.

Then the `compatible` property seems the way to go after all.

This what motivated this patch in the first place. On further analysis,
IIUC, defining bindings and schema is not needed, IMO, since the mailbox
is already defined in the ACPI spec. No need to redefine.

Ricardo