Re: [PATCH v4 0/7] firmware: smccc: Add basic SMCCC v1.2 + ARCH_SOC_ID support

From: Arnd Bergmann <arnd@arndb.de>
To: Sudeep Holla <sudeep.holla@arm.com>
Cc: Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
	Steven Price <steven.price@arm.com>,
	harb@amperecomputing.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 0/7] firmware: smccc: Add basic SMCCC v1.2 + ARCH_SOC_ID support
Date: Thu, 21 May 2020 11:06:23 +0200	[thread overview]
Message-ID: <CAK8P3a3dV0B26XE3oFQGTFf8EWV0AHoLudNtpSSB_t+pCfkOkQ@mail.gmail.com> (raw)
In-Reply-To: <20200521081055.GD1131@bogus>

On Thu, May 21, 2020 at 10:11 AM Sudeep Holla <sudeep.holla@arm.com> wrote:
> On Thu, May 21, 2020 at 08:57:56AM +0100, Will Deacon wrote:
> > On Thu, May 21, 2020 at 09:34:10AM +0200, Arnd Bergmann wrote:
> > > On Thu, May 21, 2020 at 9:07 AM Sudeep Holla <sudeep.holla@arm.com> wrote:
> > > > On Wed, May 20, 2020 at 11:54:16PM +0200, Arnd Bergmann wrote:
> > > > > On Wed, May 20, 2020 at 11:29 PM Will Deacon <will@kernel.org> wrote:
> > > > > > Applied to arm64 (for-next/smccc), thanks!
> > > > > >
> > > > > > Arnd -- Sudeep's reply to you about the sysfs groups seemed reasonable to me,
> > > > > > but please shout if you'd rather I dropped this in order to pursue an
> > > > > > alternative approach.
> > > > >
> > > > > I missed the reply earlier, thanks for pointing me to it again.
> >
> > D'oh, I took your silence as "no objections". Oh well!
> >
> > > > > I'm not entirely convinced, but don't revert it for now because of that,
> > > > > I assume we can find a solution.
> >
> > Ok, cheers. It's on a separate branch so it's easy enough to drop if
> > necessary (i.e. no reverts needed). Sudeep -- please send any extra patches
> > on top of the branch.
> >
>
> Indeed, it is also last patch in the series. However if Arnd is happy
> with the sysfs names, we can move to generic code later without breaking
> anything.
>
> We need not revert or drop it now. I will leave that to you or Arnd to
> decide. Just that it may be too late to get acks for all the soc sysfs
> drivers in time for v5.8
>
> I am fine if you want to drop the last patch.

Ok, let's drop that patch then and make sure we do something that
everyone is happy with later on. I'm already in favor of adding
a more reliable soc_device instance based on this, but we need to
be sure we don't screw up the contents of the attributes when we
can't change them later.

> > > >> drivers/firmware/smccc/smccc.c:14:13: warning: no previous prototype for function 'arm_smccc_version_init' [-Wmissing-prototypes]
> > > void __init arm_smccc_version_init(u32 version, enum arm_smccc_conduit conduit)
> > > ^
> > > drivers/firmware/smccc/smccc.c:14:1: note: declare 'static' if the
> > > function is not intended to be used outside of this translation unit
> > > void __init arm_smccc_version_init(u32 version, enum arm_smccc_conduit conduit)
> >
> > I saw that when I applied the patches, but since the function is called from
> > another compilation unit (psci/psci.o), I just ignored it as we have loads
> > of these already and it only screams if you build with W=1.
> >
>
> /me confused. Do you need the fix for this warning or you are happy to ignore?

I want a fix for that, as I hope we can eventually turn this warning on by
default and stop playing whack-a-mole when they come up. Most of these
warnings are harmless, but occasionally the prototypes don't match exactly
and cause real bugs depending on the configuration, and ensuring both
sides include a common header file is an easy way to make it work
more reliably.

Note that the warning should come up for either W=1 or C=1, and I also
think that
new code should generally be written sparse-clean and have no warnings with
'make C=1' as a rule.

      Arnd