linux-kernel - Re: [PATCH v2] cpuidle-pseries: Fix CEDE latency conversion from tb to us

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Date:   Thu, 10 Sep 2020 22:55:33 +1000 (AEST)
From:   Michael Ellerman <patch-notifications@...erman.id.au>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Joel Stanley <joel@....id.au>,
        "Gautham R. Shenoy" <ego@...ux.vnet.ibm.com>,
        Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>,
        Michael Ellerman <mpe@...erman.id.au>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v2] cpuidle-pseries: Fix CEDE latency conversion from tb to us

On Thu, 3 Sep 2020 14:57:27 +0530, Gautham R. Shenoy wrote:
> commit d947fb4c965c ("cpuidle: pseries: Fixup exit latency for
> CEDE(0)") sets the exit latency of CEDE(0) based on the latency values
> of the Extended CEDE states advertised by the platform. The values
> advertised by the platform are in timebase ticks. However the cpuidle
> framework requires the latency values in microseconds.
> 
> If the tb-ticks value advertised by the platform correspond to a value
> smaller than 1us, during the conversion from tb-ticks to microseconds,
> in the current code, the result becomes zero. This is incorrect as it
> puts a CEDE state on par with the snooze state.
> 
> [...]

Applied to powerpc/fixes.

[1/1] cpuidle: pseries: Fix CEDE latency conversion from tb to us
      https://git.kernel.org/powerpc/c/1d3ee7df009a46440c58508b8819213c09503acd

cheers