cpuidle: fix HP nx6125 regression

Fix for http://bugzilla.kernel.org/show_bug.cgi?id=9355

cpuidle always used to fallback to C2 if there is some bm activity while
entering C3. But, presence of C2 is not always guaranteed. Change cpuidle
algorithm to detect a safe_state to fallback in case of bm_activity and
use that state instead of C2.

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

3 files changed, 56 insertions, 71 deletions

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 1af0694e8520..8904f5c82a1c 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -197,6 +197,19 @@ static inline u32 ticks_elapsed_in_us(u32 t1, u32 t2)
                 return PM_TIMER_TICKS_TO_US((0xFFFFFFFF - t1) + t2);
 }
 
+static void acpi_safe_halt(void)
+{
+        current_thread_info()->status &= ~TS_POLLING;
+        /*
+         * TS_POLLING-cleared state must be visible before we
+         * test NEED_RESCHED:
+         */
+        smp_mb();
+        if (!need_resched())
+                safe_halt();
+        current_thread_info()->status |= TS_POLLING;
+}
+
 #ifndef CONFIG_CPU_IDLE
 
 static void
@@ -239,19 +252,6 @@ acpi_processor_power_activate(struct acpi_processor *pr,
         return;
 }
 
-static void acpi_safe_halt(void)
-{
-        current_thread_info()->status &= ~TS_POLLING;
-        /*
-         * TS_POLLING-cleared state must be visible before we
-         * test NEED_RESCHED:
-         */
-        smp_mb();
-        if (!need_resched())
-                safe_halt();
-        current_thread_info()->status |= TS_POLLING;
-}
-
 static atomic_t c3_cpu_count;
 
 /* Common C-state entry for C2, C3, .. */
@@ -1385,15 +1385,7 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
         if (pr->flags.bm_check)
                 acpi_idle_update_bm_rld(pr, cx);
 
-        current_thread_info()->status &= ~TS_POLLING;
-        /*
-         * TS_POLLING-cleared state must be visible before we test
-         * NEED_RESCHED:
-         */
-        smp_mb();
-        if (!need_resched())
-                safe_halt();
-        current_thread_info()->status |= TS_POLLING;
+        acpi_safe_halt();
 
         cx->usage++;
 
@@ -1493,6 +1485,15 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
         if (acpi_idle_suspend)
                 return(acpi_idle_enter_c1(dev, state));
 
+        if (acpi_idle_bm_check()) {
+                if (dev->safe_state) {
+                        return dev->safe_state->enter(dev, dev->safe_state);
+                } else {
+                        acpi_safe_halt();
+                        return 0;
+                }
+        }
+
         local_irq_disable();
         current_thread_info()->status &= ~TS_POLLING;
         /*
@@ -1515,49 +1516,39 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
          */
         acpi_state_timer_broadcast(pr, cx, 1);
 
-        if (acpi_idle_bm_check()) {
-                cx = pr->power.bm_state;
-
-                acpi_idle_update_bm_rld(pr, cx);
-
-                t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-                acpi_idle_do_entry(cx);
-                t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-        } else {
-                acpi_idle_update_bm_rld(pr, cx);
+        acpi_idle_update_bm_rld(pr, cx);
 
-                /*
-                 * disable bus master
-                 * bm_check implies we need ARB_DIS
-                 * !bm_check implies we need cache flush
-                 * bm_control implies whether we can do ARB_DIS
-                 *
-                 * That leaves a case where bm_check is set and bm_control is
-                 * not set. In that case we cannot do much, we enter C3
-                 * without doing anything.
-                 */
-                if (pr->flags.bm_check && pr->flags.bm_control) {
-                        spin_lock(&c3_lock);
-                        c3_cpu_count++;
-                        /* Disable bus master arbitration when all CPUs are in C3 */
-                        if (c3_cpu_count == num_online_cpus())
-                                acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1);
-                        spin_unlock(&c3_lock);
-                } else if (!pr->flags.bm_check) {
-                        ACPI_FLUSH_CPU_CACHE();
-                }
+        /*
+         * disable bus master
+         * bm_check implies we need ARB_DIS
+         * !bm_check implies we need cache flush
+         * bm_control implies whether we can do ARB_DIS
+         *
+         * That leaves a case where bm_check is set and bm_control is
+         * not set. In that case we cannot do much, we enter C3
+         * without doing anything.
+         */
+        if (pr->flags.bm_check && pr->flags.bm_control) {
+                spin_lock(&c3_lock);
+                c3_cpu_count++;
+                /* Disable bus master arbitration when all CPUs are in C3 */
+                if (c3_cpu_count == num_online_cpus())
+                        acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1);
+                spin_unlock(&c3_lock);
+        } else if (!pr->flags.bm_check) {
+                ACPI_FLUSH_CPU_CACHE();
+        }
 
-                t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
-                acpi_idle_do_entry(cx);
-                t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+        t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
+        acpi_idle_do_entry(cx);
+        t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
 
-                /* Re-enable bus master arbitration */
-                if (pr->flags.bm_check && pr->flags.bm_control) {
-                        spin_lock(&c3_lock);
-                        acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
-                        c3_cpu_count--;
-                        spin_unlock(&c3_lock);
-                }
+        /* Re-enable bus master arbitration */
+        if (pr->flags.bm_check && pr->flags.bm_control) {
+                spin_lock(&c3_lock);
+                acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
+                c3_cpu_count--;
+                spin_unlock(&c3_lock);
         }
 
 #if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86_TSC)
@@ -1626,12 +1617,14 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
                         case ACPI_STATE_C1:
                         state->flags |= CPUIDLE_FLAG_SHALLOW;
                         state->enter = acpi_idle_enter_c1;
+                        dev->safe_state = state;
                         break;
 
                         case ACPI_STATE_C2:
                         state->flags |= CPUIDLE_FLAG_BALANCED;
                         state->flags |= CPUIDLE_FLAG_TIME_VALID;
                         state->enter = acpi_idle_enter_simple;
+                        dev->safe_state = state;
                         break;
 
                         case ACPI_STATE_C3:
@@ -1652,14 +1645,6 @@ static int acpi_processor_setup_cpuidle(struct acpi_processor *pr)
         if (!count)
                 return -EINVAL;
 
-        /* find the deepest state that can handle active BM */
-        if (pr->flags.bm_check) {
-                for (i = 1; i < ACPI_PROCESSOR_MAX_POWER && i <= max_cstate; i++)
-                        if (pr->power.states[i].type == ACPI_STATE_C3)
-                                break;
-                pr->power.bm_state = &pr->power.states[i-1];
-        }
-
         return 0;
 }
 
diff --git a/include/acpi/processor.h b/include/acpi/processor.h
index 26d79f6db8a0..76411b1fc4fd 100644
--- a/include/acpi/processor.h
+++ b/include/acpi/processor.h
@@ -78,7 +78,6 @@ struct acpi_processor_cx {
 struct acpi_processor_power {
         struct cpuidle_device dev;
         struct acpi_processor_cx *state;
-        struct acpi_processor_cx *bm_state;
         unsigned long bm_check_timestamp;
         u32 default_state;
         u32 bm_activity;
diff --git a/include/linux/cpuidle.h b/include/linux/cpuidle.h
index 16a51546db44..c4e00161a247 100644
--- a/include/linux/cpuidle.h
+++ b/include/linux/cpuidle.h
@@ -92,6 +92,7 @@ struct cpuidle_device {
         struct kobject          kobj;
         struct completion       kobj_unregister;
         void                    *governor_data;
+        struct cpuidle_state    *safe_state;
 };
 
 DECLARE_PER_CPU(struct cpuidle_device *, cpuidle_devices);