From: "Gautham R. Shenoy" <e...@linux.vnet.ibm.com>
cpu-idle on powernv currently has support for only snooze, nap and
fastsleep states. Winkle idle state was excluded due to its large
exit-latency.
This patch adds winkle as a cpu-idle state for experimental
purposes. This state is disabled at start by default. However, should an
adventurous user want to enable it on a particular CPU(s), they can do
so by echo'ing a zero into the per-cpu sysfs cpuidle control file named
"disable" corresponding to this state.
Signed-off-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
---
drivers/cpuidle/cpuidle-powernv.c | 44 ++++++++++++++++++++++++++++++++-------
1 file changed, 36 insertions(+), 8 deletions(-)
diff --git a/drivers/cpuidle/cpuidle-powernv.c
b/drivers/cpuidle/cpuidle-powernv.c
index f7ca891..0437d8a 100644
--- a/drivers/cpuidle/cpuidle-powernv.c
+++ b/drivers/cpuidle/cpuidle-powernv.c
@@ -20,7 +20,6 @@
#include <asm/opal.h>
#include <asm/runlatch.h>
-#define POWERNV_THRESHOLD_LATENCY_NS 200000
struct cpuidle_driver powernv_idle_driver = {
.name = "powernv_idle",
@@ -95,6 +94,30 @@ static int fastsleep_loop(struct cpuidle_device *dev,
return index;
}
+
+static int winkle_loop(struct cpuidle_device *dev,
+ struct cpuidle_driver *drv,
+ int index)
+{
+ unsigned long old_lpcr = mfspr(SPRN_LPCR);
+ unsigned long new_lpcr;
+
+ if (unlikely(system_state < SYSTEM_RUNNING))
+ return index;
+
+ new_lpcr = old_lpcr;
+ /* Do not exit powersave upon decrementer as we've setup the timer
+ * offload.
+ */
+ new_lpcr &= ~LPCR_PECE1;
+
+ mtspr(SPRN_LPCR, new_lpcr);
+ power7_winkle();
+
+ mtspr(SPRN_LPCR, old_lpcr);
+
+ return index;
+}
#endif
static int stop_loop(struct cpuidle_device *dev,
@@ -246,13 +269,6 @@ static int powernv_add_idle_states(void)
"ibm,cpu-idle-state-residency-ns", residency_ns,
dt_idle_states);
for (i = 0; i < dt_idle_states; i++) {
- /*
- * If an idle state has exit latency beyond
- * POWERNV_THRESHOLD_LATENCY_NS then don't use it
- * in cpu-idle.
- */
- if (latency_ns[i] > POWERNV_THRESHOLD_LATENCY_NS)
- continue;
/*
* Cpuidle accepts exit_latency and target_residency in us.
@@ -301,6 +317,18 @@ static int powernv_add_idle_states(void)
powernv_states[nr_idle_states].enter = stop_loop;
stop_psscr_table[nr_idle_states] = psscr_val[i];
}
+
+ if (flags[i] & OPAL_PM_WINKLE_ENABLED) {
+ int state_idx = nr_idle_states;
+
+ strcpy(powernv_states[state_idx].name, "Winkle");
+ strcpy(powernv_states[state_idx].desc, "Winkle");
+ powernv_states[state_idx].flags =
+ CPUIDLE_FLAG_TIMER_STOP;
+ powernv_states[state_idx].target_residency = 500000;
+ powernv_states[state_idx].enter = winkle_loop;
+ powernv_states[state_idx].disable_use_at_start = true;
+ }
#endif
powernv_states[nr_idle_states].exit_latency =
((unsigned int)latency_ns[i]) / 1000;
--
1.9.4
