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From: Dave Martin <Dave.Martin@arm.com>
To: Mark Rutland <mark.rutland@arm.com>
Cc: lorenzo.pieralisi@arm.com, suzuki.poulose@arm.com,
	marc.zyngier@arm.com, catalin.marinas@arm.com,
	will.deacon@arm.com, linux@armlinux.org.uk, james.morse@arm.com,
	robin.murphy@arm.com, linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCHv3 1/6] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit()
Date: Tue, 13 Aug 2019 12:38:12 +0100	[thread overview]
Message-ID: <20190813113812.GW10425@arm.com> (raw)
In-Reply-To: <20190812152649.GC52896@lakrids.cambridge.arm.com>

On Mon, Aug 12, 2019 at 04:26:49PM +0100, Mark Rutland wrote:
> On Mon, Aug 12, 2019 at 04:10:43PM +0100, Dave Martin wrote:
> > On Mon, Aug 12, 2019 at 04:06:35PM +0100, Mark Rutland wrote:
> > > On Mon, Aug 12, 2019 at 04:03:29PM +0100, Dave Martin wrote:
> > > > On Fri, Aug 09, 2019 at 02:22:40PM +0100, Mark Rutland wrote:
> > > > > diff --git a/include/linux/arm-smccc.h b/include/linux/arm-smccc.h
> > > > > index 080012a6f025..df01a8579034 100644
> > > > > --- a/include/linux/arm-smccc.h
> > > > > +++ b/include/linux/arm-smccc.h
> > > > > @@ -80,6 +80,22 @@
> > > > >  
> > > > >  #include <linux/linkage.h>
> > > > >  #include <linux/types.h>
> > > > > +
> > > > > +enum arm_smccc_conduit {
> > > > > +	SMCCC_CONDUIT_NONE,
> > > > 
> > > > If this is intended to have the value 0, is it worth making that
> > > > explicit?  I can never remember whether enums start at 1 or 0 by
> > > > default...
> > > 
> > > They start at 0. I intend that checks are done explicitly against an
> > > enum value, so I'm not sure that matters.
> > 
> > Not really.
> > 
> > It depends whether code like if (!arm_smccc_1_1_get_conduit()) { ... }
> > is considered sane or not.
> > 
> > If we don't think people should be doing this, omitting the explicit
> > value specifier seems fine.
> 
> My expectation was that they'd check explicitly against
> SMCCC_CONDUIT_NONE, since all of the existing callers care about the
> specific conduit for other reasons (e.g. patching).
> 
> I also expect to wrap this in a sbusequent patch that provides helpers:
> 
> * arm_smccc_1_1_available()
> * arm_smccc_1_1_call(...)
> 
> ... for the cases where we just want to make a call and don't care about
> the specific conduit.

Seems reasonable.

Cheers
---Dave

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  reply	other threads:[~2019-08-13 11:40 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-09 13:22 [PATCHv3 0/6] arm/arm64: SMCCC conduit cleanup Mark Rutland
2019-08-09 13:22 ` [PATCHv3 1/6] arm/arm64: smccc/psci: add arm_smccc_1_1_get_conduit() Mark Rutland
2019-08-12 15:03   ` Dave Martin
2019-08-12 15:06     ` Mark Rutland
2019-08-12 15:10       ` Dave Martin
2019-08-12 15:26         ` Mark Rutland
2019-08-13 11:38           ` Dave Martin [this message]
2019-08-09 13:22 ` [PATCHv3 2/6] arm64: errata: use arm_smccc_1_1_get_conduit() Mark Rutland
2019-08-09 13:22 ` [PATCHv3 3/6] arm: spectre-v2: " Mark Rutland
2019-10-11 14:02   ` Catalin Marinas
2019-08-09 13:22 ` [PATCHv3 4/6] firmware/psci: use common SMCCC_CONDUIT_* Mark Rutland
2019-08-09 13:22 ` [PATCHv3 5/6] firmware: arm_sdei: " Mark Rutland
2019-08-09 13:22 ` [PATCHv3 6/6] smccc: make 1.1 macros value-returning Mark Rutland
2019-08-15 16:42   ` Will Deacon
2019-08-19 10:44     ` Mark Rutland

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