Messages in this thread | | | Date | Wed, 30 Apr 2014 14:40:31 +0200 | From | Daniel Lezcano <> | Subject | Re: [PATCH 2/2] cpuidle / menu: Return error code if there are no suitable states |
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On 04/29/2014 01:28 AM, Rafael J. Wysocki wrote: > On Monday, April 28, 2014 01:14:32 PM Daniel Lezcano wrote: >> On 04/27/2014 02:55 PM, Rafael J. Wysocki wrote: >>> From: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >>> >>> If there is a PM QoS latency limit and all of the sufficiently shallow >>> C-states are disabled, the cpuidle menu governor returns 0 which on >>> some systems is CPUIDLE_DRIVER_STATE_START and shouldn't be returned >>> if that C-state has been disabled. >>> >>> Fix the issue by modifying the menu governor to return an error code >>> in such situations. >>> >>> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com> >>> --- >>> drivers/cpuidle/governors/menu.c | 2 +- >>> include/linux/cpuidle.h | 2 ++ >>> 2 files changed, 3 insertions(+), 1 deletion(-) >>> >>> Index: linux-pm/drivers/cpuidle/governors/menu.c >>> =================================================================== >>> --- linux-pm.orig/drivers/cpuidle/governors/menu.c >>> +++ linux-pm/drivers/cpuidle/governors/menu.c >>> @@ -296,7 +296,7 @@ static int menu_select(struct cpuidle_dr >>> data->needs_update = 0; >>> } >>> >>> - data->last_state_idx = 0; >>> + data->last_state_idx = CPUIDLE_DRIVER_STATE_POLL; >>> >>> /* Special case when user has set very strict latency requirement */ >>> if (unlikely(latency_req == 0)) >>> Index: linux-pm/include/linux/cpuidle.h >>> =================================================================== >>> --- linux-pm.orig/include/linux/cpuidle.h >>> +++ linux-pm/include/linux/cpuidle.h >>> @@ -217,8 +217,10 @@ static inline int cpuidle_register_gover >>> >>> #ifdef CONFIG_ARCH_HAS_CPU_RELAX >>> #define CPUIDLE_DRIVER_STATE_START 1 >>> +#define CPUIDLE_DRIVER_STATE_POLL 0 >>> #else >>> #define CPUIDLE_DRIVER_STATE_START 0 >>> +#define CPUIDLE_DRIVER_STATE_POLL (-ENXIO) >>> #endif >>> >>> #endif /* _LINUX_CPUIDLE_H */ >> >> Hi Rafael, >> >> CPUIDLE_DRIVER_STATE_START is only for x86. It introduces some confusion >> in the code. > > I won't disagree with that. > >> As only two drivers are concerned by it, wouldn't make >> sense to add the poll state to those driver directly instead of having >> the code hacked around ? (eg. insert the poll state in the common >> cpuidle code). > > Well, what about initializing data->last_state_idx to > (CPUIDLE_DRIVER_STATE_START - 1) in menu_select() instead of introducing the > new symbol for the time being and getting rid of CPUIDLE_DRIVER_STATE_START > separately?
+1
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