linux-kernel - Re: [PATCH v5 0/4] arm64: SPE ACPI enablement

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Date:   Thu, 27 Jun 2019 17:47:06 +0100
From:   Will Deacon <will@...nel.org>
To:     Jeremy Linton <jeremy.linton@....com>
Cc:     linux-arm-kernel@...ts.infradead.org, mark.rutland@....com,
        lorenzo.pieralisi@....com, will.deacon@....com,
        sudeep.holla@....com, rjw@...ysocki.net,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        catalin.marinas@....com, lenb@...nel.org
Subject: Re: [PATCH v5 0/4] arm64: SPE ACPI enablement

On Wed, Jun 26, 2019 at 04:37:14PM -0500, Jeremy Linton wrote:
> This patch series enables the Arm Statistical Profiling
> Extension (SPE) on ACPI platforms.
> 
> This is possible because ACPI 6.3 uses a previously
> reserved field in the MADT to store the SPE interrupt
> number, similarly to how the normal PMU is described.
> If a consistent valid interrupt exists across all the
> cores in the system, a platform device is registered.
> That then triggers the SPE module, which runs as normal.
> 
> We also add the ability to parse the PPTT for IDENTICAL
> cores. We then use this to sanity check the single SPE
> device we create. This creates a bit of a problem with
> respect to the specification though. The specification
> says that its legal for multiple tree's to exist in the
> PPTT. We handle this fine, but what happens in the
> case of multiple tree's is that the lack of a common
> node with IDENTICAL set forces us to assume that there
> are multiple non-IDENTICAL cores in the machine.
> 
> v4->v5: Remove error returns from arm_spe_acpi_register_device()
> 	Add some review/test tags

Cheers, I've pushed this out with the acks and typo fixes.

https://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git/log/?h=for-next/perf

Please let me know if you spot any problems.

Will