Re: [PATCH v3] mailbox: add list of used channels to debugfs

From: Wolfram Sang

Date: Tue Apr 14 2026 - 11:31:41 EST


Hi Geert,

> > Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
>
> Thanks for your patch, which looks useful!

Glad you like it!

> Can you please put it in a subdir, like all other summaries:

Sadly not, because of the paragraph from above:

> > Note that mailbox controllers currently can be instantiated at any
> > initcall stage. So, per-controller debugfs handling was discarded
> > because it is not clear when to create the root "mailbox"-debugfs entry.
> > A central file was chosen, similar to the GPIO subsystem, which is
> > independent of the initcall stage because it will be accessed only when
> > userspace is available anyhow.

I would need to use core_initcall for the mailbox-subsys. debugfs itself
also uses core_initcall. Then, some drivers (e.g. hi3660-mailbox) use
core_initcall. I don't think the subdir is worth all the potential race
conditions and fragile solutions which usually come with it. Or do you
know a solid solution to this problem?

Happy hacking,

Wolfram

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