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 <[email protected]> > > > > 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 <[email protected]> > > --- > > 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? -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
