[PATCH] clocksource/drivers/arm_arch_timer: limit XGene-1 workaround

[Oliver Upton]

On Mon, Oct 16, 2023 at 04:31:27PM +0100, Andre Przywara wrote:
> The AppliedMicro XGene-1 CPU has an erratum where the timer condition
> would only consider TVAL, not CVAL. We currently apply a workaround when
> seeing the PartNum field of MIDR_EL1 being 0x000, under the assumption
> that this would match only the XGene-1 CPU model.
> However even the Ampere eMAG (aka XGene-3) uses that same part number, and
> only differs in the "Variant" and "Revision" fields: XGene-1's MIDR is
> 0x500f0000, our eMAG reports 0x503f0002. Experiments show the latter
> doesn't show the faulty behaviour.
> 
> Increase the specificity of the check to only consider partnum 0x000 and
> variant 0x00, to exclude the Ampere eMAG.
> 
> Fixes: 012f18850452 ("clocksource/drivers/arm_arch_timer: Work around broken CVAL implementations")
> Reported-by: Ross Burton <ross.burton at arm.com>
> Signed-off-by: Andre Przywara <andre.przywara at arm.com>

Reviewed-by: Oliver Upton <oliver.upton at linux.dev>

-- 
Thanks,
Oliver