linux-kernel - Re: [PATCH 1/2] arm64/sysreg: Move TRFCR definitions to sysreg

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Message-ID: <016cbd81-3aad-4160-88b7-13aa303e1821@sirena.org.uk>
Date:   Fri, 4 Aug 2023 17:03:48 +0100
From:   Mark Brown <broonie@...nel.org>
To:     James Clark <james.clark@....com>
Cc:     coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Mike Leach <mike.leach@...aro.org>,
        Leo Yan <leo.yan@...aro.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        James Morse <james.morse@....com>,
        Kristina Martsenko <kristina.martsenko@....com>,
        Anshuman Khandual <anshuman.khandual@....com>,
        Rob Herring <robh@...nel.org>,
        Jintack Lim <jintack.lim@...aro.org>,
        Joey Gouly <joey.gouly@....com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] arm64/sysreg: Move TRFCR definitions to sysreg

On Fri, Aug 04, 2023 at 04:55:19PM +0100, James Clark wrote:
> On 04/08/2023 13:10, Mark Brown wrote:
> > On Fri, Aug 04, 2023 at 09:52:16AM +0100, James Clark wrote:

> >> TRFCR_EL2_CX needs to become TRFCR_ELx_CX to avoid unnecessary
> >> duplication and make the SysregFields block re-usable.

> > That field is only present in the EL2 version.  I would tend to leave
> > the registers split for that reason, there's some minor potential for
> > confusion if people refer to the sysreg file rather than the docs, or
> > potentially confuse some future automation.  However that's not a super
> > strongly held opinion.

> True, the potential for confusion is a good reason to not try to avoid
> duplication. Probably helps if it is ever auto generated or validated as
> well.

> I could update it on the next version. But do I leave all the existing
> _ELx usages in the code, or change them all to _EL1 (Except CX_EL2)? To
> leave them as _ELx sysreg would look like this, even though _EL1 would
> probably be more accurate:

>   SysregFields TRFCR_EL2

You could just leave this as _ELx and simply not reference it for the
EL1 definition which is proably fair?  Perhaps with a comment saying why
there's an expanded definition for EL1.  I don't think it fundamentally
matters which way it's done so long as EL1 stays a subset of the EL2
definition (which seems likely, and we can always revisit should that
happen).

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