Re: [PATCH] cpuidle: Do not use CPUIDLE_DRIVER_STATE_START in cpuidle.c

[Daniel Lezcano]

On 05/27/2015 03:36 AM, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>
> The CPUIDLE_DRIVER_STATE_START symbol is defined as 1 only if
> CONFIG_ARCH_HAS_CPU_RELAX is set, otherwise it is defined as 0.
> However, if CONFIG_ARCH_HAS_CPU_RELAX is set, the first (index 0)
> entry in the cpuidle driver's table of states is overwritten with
> the default "poll" entry by the core.  The "state" defined by the
> "poll" entry doesn't provide ->enter_dead and ->enter_freeze
> callbacks and its exit_latency is 0.
>
> For this reason, it is not necessary to use CPUIDLE_DRIVER_STATE_START
> in cpuidle_play_dead() (->enter_dead is NULL, so the "poll state"
> will be skipped by the loop) and in find_deepest_state() (since
> exit_latency is 0, the "poll state" will become the default if the
> "s->exit_latency <= latency_req" check is replaced with
> "s->exit_latency < latency_req" which may only matter for drivers
> providing different states with the same exit_latency).
>
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

I was about to send *exactly* the same patch :)

Acked-by: Daniel Lezcano <daniel.lezcano@xxxxxxxxxx>


--
 <http://www.linaro.org/> Linaro.org â Open source software for ARM SoCs

Follow Linaro:  <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/