From: Oliver Upton <oliver.upton@linux.dev>
To: Andre Przywara <andre.przywara@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>, Marc Zyngier <maz@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Zenghui Yu <yuzenghui@huawei.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Thomas Gleixner <tglx@linutronix.de>,
Rob Herring <robh@kernel.org>, Ross Burton <ross.burton@arm.com>,
Khuong Dinh <khuong@os.amperecomputing.com>,
Yang Shi <yang@os.amperecomputing.com>,
D Scott Phillips <scott@os.amperecomputing.com>,
Ilkka Koskinen <ilkka@os.amperecomputing.com>,
Joe Korty <joe.korty@concurrent-rt.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH] clocksource/drivers/arm_arch_timer: limit XGene-1 workaround
Date: Mon, 16 Oct 2023 19:19:20 +0000 [thread overview]
Message-ID: <ZS2MuAZi_la0zVnW@linux.dev> (raw)
In-Reply-To: <20231016153127.116101-1-andre.przywara@arm.com>
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@arm.com>
> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Oliver Upton <oliver.upton@linux.dev>
--
Thanks,
Oliver
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next prev parent reply other threads:[~2023-10-16 19:19 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-16 15:31 [PATCH] clocksource/drivers/arm_arch_timer: limit XGene-1 workaround Andre Przywara
2023-10-16 16:54 ` Marc Zyngier
2023-10-16 19:19 ` Oliver Upton [this message]
2023-10-18 10:15 ` Catalin Marinas
2023-10-24 14:58 ` Daniel Lezcano
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