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| author | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-01-14 23:24:22 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2016-01-14 23:24:22 +0100 |
| commit | 9c4b2867ed7c8c8784dd417ffd16e705e81eb145 (patch) | |
| tree | cdb9a119d25dfd0347551b26d45ff6a95750ba75 /drivers/cpuidle | |
| parent | 84599238ea78d98136fc6f6239a14083128ecf8b (diff) | |
| download | lwn-9c4b2867ed7c8c8784dd417ffd16e705e81eb145.tar.gz lwn-9c4b2867ed7c8c8784dd417ffd16e705e81eb145.zip | |
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/cpuidle')
| -rw-r--r-- | drivers/cpuidle/governors/menu.c | 21 |
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 |