Re: [PATCH] cpufreq: conservative: Fix next frequency selection

From: Viresh Kumar
Date: Thu Oct 13 2016 - 02:26:25 EST

On 12-10-16, 21:47, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> Commit d352cf47d93e (cpufreq: conservative: Do not use transition
> notifications) overlooked the case when the "frequency step" used
> by the conservative governor is small relative to the distances
> between the available frequencies and broke the algorithm by
> using policy->cur instead of the previously requested frequency
> when computing the next one.
> As a result, the governor may not be able to go outside of a narrow
> range between two consecutive available frequencies.
> Fix the problem by making the governor save the previously requested
> frequency and select the next one relative that value (unless it is
> out of range, in which case policy->cur will be used instead).
> Fixes: d352cf47d93e (cpufreq: conservative: Do not use transition notifications)
> Link:
> Reported-and-tested-by: Aleksey Rybalkin <aleksey@xxxxxxxxxxxx>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> drivers/cpufreq/cpufreq_conservative.c | 19 ++++++++++++++++---
> 1 file changed, 16 insertions(+), 3 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx>