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authorZhao Yakui <yakui.zhao@intel.com>2007-11-15 16:59:30 +0800
committerLen Brown <len.brown@intel.com>2007-11-16 21:34:49 -0500
commitef54d5ad2f58f899be6419fd1090cdeb2439851a (patch)
tree3ebed37b1168bd408e567c05d5a841fbe72c0a77 /drivers/acpi/processor_throttling.c
parent8c0863403f109a43d7000b4646da4818220d501f (diff)
ACPI: Enforce T-state limit changes immediately
When a T-state limit change notification is received, Linux must evaluate _TPC and change its current T-state immediately to comply with the new limit. Previously, Linux would notice the new limit only upon the next throttling change. Signed-off-by: Zhao Yakui <yakui.zhao@intel.com> Signed-off-by: Li Shaohua <shaohua.li@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi/processor_throttling.c')
-rw-r--r--drivers/acpi/processor_throttling.c50
1 files changed, 49 insertions, 1 deletions
diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index 0b8204e7082..5fa8ac1c0c8 100644
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -70,7 +70,55 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
int acpi_processor_tstate_has_changed(struct acpi_processor *pr)
{
- return acpi_processor_get_platform_limit(pr);
+ int result = 0;
+ int throttling_limit;
+ int current_state;
+ struct acpi_processor_limit *limit;
+ int target_state;
+
+ result = acpi_processor_get_platform_limit(pr);
+ if (result) {
+ /* Throttling Limit is unsupported */
+ return result;
+ }
+
+ throttling_limit = pr->throttling_platform_limit;
+ if (throttling_limit >= pr->throttling.state_count) {
+ /* Uncorrect Throttling Limit */
+ return -EINVAL;
+ }
+
+ current_state = pr->throttling.state;
+ if (current_state > throttling_limit) {
+ /*
+ * The current state can meet the requirement of
+ * _TPC limit. But it is reasonable that OSPM changes
+ * t-states from high to low for better performance.
+ * Of course the limit condition of thermal
+ * and user should be considered.
+ */
+ limit = &pr->limit;
+ target_state = throttling_limit;
+ if (limit->thermal.tx > target_state)
+ target_state = limit->thermal.tx;
+ if (limit->user.tx > target_state)
+ target_state = limit->user.tx;
+ } else if (current_state == throttling_limit) {
+ /*
+ * Unnecessary to change the throttling state
+ */
+ return 0;
+ } else {
+ /*
+ * If the current state is lower than the limit of _TPC, it
+ * will be forced to switch to the throttling state defined
+ * by throttling_platfor_limit.
+ * Because the previous state meets with the limit condition
+ * of thermal and user, it is unnecessary to check it again.
+ */
+ target_state = throttling_limit;
+ }
+ return acpi_processor_set_throttling(pr, target_state);
}
/*