| Message ID | 20201024162953.14142-1-yu.c.chen@intel.com (mailing list archive) |
|---|---|
| State | Mainlined, archived |
| Headers | show |
| Series | intel_idle: Fix max_cstate for processor models without C-state tables | expand |
On Sat, Oct 24, 2020 at 6:27 PM Chen Yu <yu.c.chen@intel.com> wrote: > > Currently intel_idle driver gets the c-state information from ACPI > _CST if the processor model is not recognized by it. However the > c-state in _CST starts with index 1 which is different from the > index in intel_idle driver's internal c-state table. While > intel_idle_max_cstate_reached() was previously introduced to > deal with intel_idle driver's internal c-state table, re-using > this function directly on _CST might get wrong. Fix this by > subtracting the index by 1 when checking max cstate via _CST. > For example, append intel_idle.max_cstate=1 in boot command line, > Before the patch: > grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/name > POLL > After the patch: > grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/name > /sys/devices/system/cpu/cpu0/cpuidle/state0/name:POLL > /sys/devices/system/cpu/cpu0/cpuidle/state1/name:C1_ACPI > > Fixes: 18734958e9bf ("intel_idle: Use ACPI _CST for processor models without C-state tables") > Reported-by: Pengfei Xu <pengfei.xu@intel.com> > Cc: 5.6+ <stable@vger.kernel.org> # 5.6+ > Signed-off-by: Chen Yu <yu.c.chen@intel.com> > --- > drivers/idle/intel_idle.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c > index 9a810e4a7946..dbd4be1c271b 100644 > --- a/drivers/idle/intel_idle.c > +++ b/drivers/idle/intel_idle.c > @@ -1236,7 +1236,7 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) > struct acpi_processor_cx *cx; > struct cpuidle_state *state; > > - if (intel_idle_max_cstate_reached(cstate)) > + if (intel_idle_max_cstate_reached(cstate - 1)) > break; > > cx = &acpi_state_table.states[cstate]; > -- Applied as 5.10-rc material with some changelog edits, thanks!
diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c index 9a810e4a7946..dbd4be1c271b 100644 --- a/drivers/idle/intel_idle.c +++ b/drivers/idle/intel_idle.c @@ -1236,7 +1236,7 @@ static void __init intel_idle_init_cstates_acpi(struct cpuidle_driver *drv) struct acpi_processor_cx *cx; struct cpuidle_state *state; - if (intel_idle_max_cstate_reached(cstate)) + if (intel_idle_max_cstate_reached(cstate - 1)) break; cx = &acpi_state_table.states[cstate];
Currently intel_idle driver gets the c-state information from ACPI _CST if the processor model is not recognized by it. However the c-state in _CST starts with index 1 which is different from the index in intel_idle driver's internal c-state table. While intel_idle_max_cstate_reached() was previously introduced to deal with intel_idle driver's internal c-state table, re-using this function directly on _CST might get wrong. Fix this by subtracting the index by 1 when checking max cstate via _CST. For example, append intel_idle.max_cstate=1 in boot command line, Before the patch: grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/name POLL After the patch: grep . /sys/devices/system/cpu/cpu0/cpuidle/state*/name /sys/devices/system/cpu/cpu0/cpuidle/state0/name:POLL /sys/devices/system/cpu/cpu0/cpuidle/state1/name:C1_ACPI Fixes: 18734958e9bf ("intel_idle: Use ACPI _CST for processor models without C-state tables") Reported-by: Pengfei Xu <pengfei.xu@intel.com> Cc: 5.6+ <stable@vger.kernel.org> # 5.6+ Signed-off-by: Chen Yu <yu.c.chen@intel.com> --- drivers/idle/intel_idle.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)