PM / QoS: CPU C-state breakage with PM Qos change
Looks like change "PM QoS: Move and rename the implementation files"
merged during the 3.2 development cycle made PM QoS depend on
CONFIG_PM which depends on (PM_SLEEP || PM_RUNTIME).
That breaks CPU C-states with kernels not having these CONFIGs, causing CPUs
to spend time in Polling loop idle instead of going into deep C-states,
consuming way way more power. This is with either acpi idle or intel idle
enabled.
Either CONFIG_PM should be enabled with any pm_qos users or
the !CONFIG_PM pm_qos_request() should return sane defaults not to break
the existing users. Here's is the patch for the latter option.
[rjw: Modified the changelog slightly.]
Signed-off-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: stable@vger.kernel.org
diff --git a/include/linux/pm_qos.h b/include/linux/pm_qos.h
index e5bbcba..4d99e4e 100644
--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -110,7 +110,19 @@
{ return; }
static inline int pm_qos_request(int pm_qos_class)
- { return 0; }
+{
+ switch (pm_qos_class) {
+ case PM_QOS_CPU_DMA_LATENCY:
+ return PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
+ case PM_QOS_NETWORK_LATENCY:
+ return PM_QOS_NETWORK_LAT_DEFAULT_VALUE;
+ case PM_QOS_NETWORK_THROUGHPUT:
+ return PM_QOS_NETWORK_THROUGHPUT_DEFAULT_VALUE;
+ default:
+ return PM_QOS_DEFAULT_VALUE;
+ }
+}
+
static inline int pm_qos_add_notifier(int pm_qos_class,
struct notifier_block *notifier)
{ return 0; }