Re: [linux-next:master 9185/10024] drivers/pmdomain/mediatek/airoha-cpu-pmdomain.c:59:2: error: write to reserved register 'R7'

[Sudeep Holla <sudeep.holla@arm.com>]

On Mon, Jan 20, 2025 at 02:37:19PM +0100, Christian Marangi (Ansuel) wrote:
> Il giorno lun 20 gen 2025 alle ore 14:34 Sudeep Holla
> <sudeep.holla@arm.com> ha scritto:
> >
> > On Mon, Jan 20, 2025 at 02:01:30PM +0100, Ulf Hansson wrote:
> > > + Sudeep,
> > >
> > > On Mon, 20 Jan 2025 at 11:37, Christian Marangi (Ansuel)
> > > <ansuelsmth@gmail.com> wrote:

[...]

> > > >
> > > > Mhhhh.... Any idea how to fix this? Maybe we have to exclude some flags?
> > > > Error is "error: write to reserved register 'R7'" and I guess it's very specific
> > > > to some kind of ARM ERRATA.
> > >
> > > I don't know to be honest. The arm-scmi transport driver
> > > (drivers/firmware/arm_scmi/transports/smc.c) is having similar calls
> > > with 9 parameters to arm_smccc_1_1_invoke(). Not sure why it's a
> > > problem here and not there?
> > >
> >
> > I think it is known issue and must be solved with the below patch if my
> > understanding is right.
> >
> 
> If it's a known issue and affects also other use of smcc why we need
> specific fix in the driver makefile instead of a more generic one.
>

IIUC, arm_smccc_1_1_invoke() is a macro which can be used anywhere.
There are reasons why we can't move it to a module and export it.

> Do you have a link for the known issue?
>

Nothing handy, but quick google search gave me this:
https://bugs.llvm.org/show_bug.cgi?id=45826

--
Regards,
Sudeep