Re: [PATCH 2/2] cpuidle / menu: Return error code if there are no suitable states
From: Daniel Lezcano
Date: Wed Apr 30 2014 - 08:40:35 EST
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@xxxxxxxxx>
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@xxxxxxxxx>
---
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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