linux-kernel - [patch 30/86] PM / QoS: CPU C-state breakage with PM Qos change

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Date:	Fri, 10 Feb 2012 14:29:49 -0800
From:	Greg KH <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Venkatesh Pallipadi <venki@...gle.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: [patch 30/86] PM / QoS: CPU C-state breakage with PM Qos change

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Venkatesh Pallipadi <venki@...gle.com>

commit d020283dc694c9ec31b410f522252f7a8397e67d upstream.

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@...gle.com>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 include/linux/pm_qos.h |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/include/linux/pm_qos.h
+++ b/include/linux/pm_qos.h
@@ -107,7 +107,19 @@ static inline void pm_qos_remove_request
 			{ 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; }

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