ACPI: Enforce T-state limit changes immediately

[linux-2.6] / drivers / acpi / processor_throttling.c

diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
index dc5b85932ea2f41a2c8611af3f591aaa7a6ce6fe..5fa8ac1c0c8497b642453185dc0041cf16beee88 100644 (file)
--- a/drivers/acpi/processor_throttling.c
+++ b/drivers/acpi/processor_throttling.c
@@ -47,6 +47,9 @@ ACPI_MODULE_NAME("processor_throttling");
 static int acpi_processor_get_throttling(struct acpi_processor *pr);
 int acpi_processor_set_throttling(struct acpi_processor *pr, int state);
 
+/*
+ * _TPC - Throttling Present Capabilities
+ */
 static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
 {
        acpi_status status = 0;
@@ -55,8 +58,10 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)
        if (!pr)
                return -EINVAL;
        status = acpi_evaluate_integer(pr->handle, "_TPC", NULL, &tpc);
-       if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
-               ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TPC"));
+       if (ACPI_FAILURE(status)) {
+               if (status != AE_NOT_FOUND) {
+                       ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TPC"));
+               }
                return -ENODEV;
        }
        pr->throttling_platform_limit = (int)tpc;
@@ -65,12 +70,60 @@ 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);
 }
 
-/* --------------------------------------------------------------------------
-                             _PTC, _TSS, _TSD support 
-   -------------------------------------------------------------------------- */
+/*
+ * _PTC - Processor Throttling Control (and status) register location
+ */
 static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
 {
        int result = 0;
@@ -81,7 +134,9 @@ static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
 
        status = acpi_evaluate_object(pr->handle, "_PTC", NULL, &buffer);
        if (ACPI_FAILURE(status)) {
-               ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PTC"));
+               if (status != AE_NOT_FOUND) {
+                       ACPI_EXCEPTION((AE_INFO, status, "Evaluating _PTC"));
+               }
                return -ENODEV;
        }
 
@@ -132,6 +187,10 @@ static int acpi_processor_get_throttling_control(struct acpi_processor *pr)
 
        return result;
 }
+
+/*
+ * _TSS - Throttling Supported States
+ */
 static int acpi_processor_get_throttling_states(struct acpi_processor *pr)
 {
        int result = 0;
@@ -144,7 +203,9 @@ static int acpi_processor_get_throttling_states(struct acpi_processor *pr)
 
        status = acpi_evaluate_object(pr->handle, "_TSS", NULL, &buffer);
        if (ACPI_FAILURE(status)) {
-               ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSS"));
+               if (status != AE_NOT_FOUND) {
+                       ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSS"));
+               }
                return -ENODEV;
        }
 
@@ -201,6 +262,10 @@ static int acpi_processor_get_throttling_states(struct acpi_processor *pr)
 
        return result;
 }
+
+/*
+ * _TSD - T-State Dependencies
+ */
 static int acpi_processor_get_tsd(struct acpi_processor *pr)
 {
        int result = 0;
@@ -213,6 +278,9 @@ static int acpi_processor_get_tsd(struct acpi_processor *pr)
 
        status = acpi_evaluate_object(pr->handle, "_TSD", NULL, &buffer);
        if (ACPI_FAILURE(status)) {
+               if (status != AE_NOT_FOUND) {
+                       ACPI_EXCEPTION((AE_INFO, status, "Evaluating _TSD"));
+               }
                return -ENODEV;
        }
 
@@ -525,9 +593,6 @@ int acpi_processor_get_throttling_info(struct acpi_processor *pr)
        int result = 0;
        int step = 0;
        int i = 0;
-       int no_ptc = 0;
-       int no_tss = 0;
-       int no_tsd = 0;
 
        ACPI_DEBUG_PRINT((ACPI_DB_INFO,
                          "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
@@ -538,12 +603,14 @@ int acpi_processor_get_throttling_info(struct acpi_processor *pr)
        if (!pr)
                return -EINVAL;
 
-       /* TBD: Support ACPI 2.0 objects */
-       no_ptc = acpi_processor_get_throttling_control(pr);
-       no_tss = acpi_processor_get_throttling_states(pr);
-       no_tsd = acpi_processor_get_tsd(pr);
-
-       if (no_ptc || no_tss) {
+       /*
+        * Evaluate _PTC, _TSS and _TPC
+        * They must all be present or none of them can be used.
+        */
+       if (acpi_processor_get_throttling_control(pr) ||
+               acpi_processor_get_throttling_states(pr) ||
+               acpi_processor_get_platform_limit(pr))
+       {
                pr->throttling.acpi_processor_get_throttling =
                    &acpi_processor_get_throttling_fadt;
                pr->throttling.acpi_processor_set_throttling =
@@ -555,6 +622,8 @@ int acpi_processor_get_throttling_info(struct acpi_processor *pr)
                    &acpi_processor_set_throttling_ptc;
        }
 
+       acpi_processor_get_tsd(pr);
+
        if (!pr->throttling.address) {
                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
                return 0;