Thread (9 messages) 9 messages, 4 authors, 2019-06-27

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

From: Will Deacon <will@kernel.org>
Date: 2019-06-27 16:47:14
Also in: linux-acpi, lkml

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

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