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authorRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-01-15 01:24:22 +0300
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2016-01-15 01:24:22 +0300
commit9c4b2867ed7c8c8784dd417ffd16e705e81eb145 (patch)
treecdb9a119d25dfd0347551b26d45ff6a95750ba75 /drivers
parent84599238ea78d98136fc6f6239a14083128ecf8b (diff)
downloadlinux-9c4b2867ed7c8c8784dd417ffd16e705e81eb145.tar.xz
cpuidle: menu: Fix menu_select() for CPUIDLE_DRIVER_STATE_START == 0
Commit a9ceb78bc75c (cpuidle,menu: use interactivity_req to disable polling) exposed a bug in menu_select() causing it to return -1 on systems with CPUIDLE_DRIVER_STATE_START equal to zero, although it should have returned 0. As a result, idle states are not entered by CPUs on those systems. Namely, on the systems in question data->last_state_idx is initially equal to -1 and the above commit modified the condition that would have caused it to be changed to 0 to be less likely to trigger which exposed the problem. However, setting data->last_state_idx initially to -1 doesn't make sense at all and on the affected systems it should always be set to CPUIDLE_DRIVER_STATE_START (ie. 0) unconditionally, so make that happen. Fixes: a9ceb78bc75c (cpuidle,menu: use interactivity_req to disable polling) Reported-and-tested-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/cpuidle/governors/menu.c21
1 files changed, 12 insertions, 9 deletions
diff --git a/drivers/cpuidle/governors/menu.c b/drivers/cpuidle/governors/menu.c
index 7b0971d97cc3..be0bae0b41e9 100644
--- a/drivers/cpuidle/governors/menu.c
+++ b/drivers/cpuidle/governors/menu.c
@@ -294,8 +294,6 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
data->needs_update = 0;
}
- data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1;
-
/* Special case when user has set very strict latency requirement */
if (unlikely(latency_req == 0))
return 0;
@@ -326,14 +324,19 @@ static int menu_select(struct cpuidle_driver *drv, struct cpuidle_device *dev)
if (latency_req > interactivity_req)
latency_req = interactivity_req;
- /*
- * We want to default to C1 (hlt), not to busy polling
- * unless the timer is happening really really soon.
- */
- if (interactivity_req > 20 &&
- !drv->states[CPUIDLE_DRIVER_STATE_START].disabled &&
- dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0)
+ if (CPUIDLE_DRIVER_STATE_START > 0) {
+ data->last_state_idx = CPUIDLE_DRIVER_STATE_START - 1;
+ /*
+ * We want to default to C1 (hlt), not to busy polling
+ * unless the timer is happening really really soon.
+ */
+ if (interactivity_req > 20 &&
+ !drv->states[CPUIDLE_DRIVER_STATE_START].disabled &&
+ dev->states_usage[CPUIDLE_DRIVER_STATE_START].disable == 0)
+ data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+ } else {
data->last_state_idx = CPUIDLE_DRIVER_STATE_START;
+ }
/*
* Find the idle state with the lowest power while satisfying