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

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Date:   Fri, 4 Aug 2023 16:55:19 +0100
From:   James Clark <james.clark@....com>
To:     Mark Brown <broonie@...nel.org>
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 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
  Res0	63:7
  UnsignedEnum	6:5	TS
  	0b0001	VIRTUAL
  	0b0010	GUEST_PHYSICAL
  	0b0011	PHYSICAL
  EndEnum
  Res0	4
  Field	3	CX
  Res0	2
  Field	1	E2TRE
  Field	0	E0TRE
  EndSysregFields

  SysregFields TRFCR_ELx
  Res0	63:7
  UnsignedEnum	6:5	TS
  	0b0001	VIRTUAL
  	0b0010	GUEST_PHYSICAL
  	0b0011	PHYSICAL
  EndEnum
  Res0	4:2
  Field	1	ExTRE
  Field	0	E0TRE
  EndSysregFields

  Sysreg	TRFCR_EL1	3	0	1	2	1
  Fields	TRFCR_ELx
  EndSysreg

  Sysreg	TRFCR_EL2	3	4	1	2	1
  Fields	TRFCR_EL2
  EndSysreg

  Sysreg TRFCR_EL12	3	5	1	2	1
  Fields	TRFCR_ELx
  EndSysreg


> Otherwise this checks out against DDI0601 2023-06:
> 
> Reviewed-by: Mark Brown <broonie@...nel.org>

Thanks for the review