Patch "ARM: mvebu: Disable CPU Idle on Armada 38x" has been added to the 3.19-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ARM: mvebu: Disable CPU Idle on Armada 38x

to the 3.19-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     arm-mvebu-disable-cpu-idle-on-armada-38x.patch
and it can be found in the queue-3.19 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 548ae94c1cc7fc120848757249b9a542b1080ffb Mon Sep 17 00:00:00 2001
From: Gregory CLEMENT <gregory.clement@free-electrons.com>
Date: Fri, 30 Jan 2015 12:34:25 +0100
Subject: ARM: mvebu: Disable CPU Idle on Armada 38x

From: Gregory CLEMENT <gregory.clement@free-electrons.com>

commit 548ae94c1cc7fc120848757249b9a542b1080ffb upstream.

On Armada 38x SoCs, under heavy I/O load, the system hangs when CPU
Idle is enabled. Waiting for a solution to this issue, this patch
disables the CPU Idle support for this SoC.

As CPU Hot plug support also uses some of the CPU Idle functions it is
also affected by the same issue. This patch disables it also for the
Armada 38x SoCs.

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/arm/mach-mvebu/pmsu.c |   16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

--- a/arch/arm/mach-mvebu/pmsu.c
+++ b/arch/arm/mach-mvebu/pmsu.c
@@ -415,6 +415,9 @@ static __init int armada_38x_cpuidle_ini
 	void __iomem *mpsoc_base;
 	u32 reg;
 
+	pr_warn("CPU idle is currently broken on Armada 38x: disabling");
+	return 0;
+
 	np = of_find_compatible_node(NULL, NULL,
 				     "marvell,armada-380-coherency-fabric");
 	if (!np)
@@ -476,6 +479,16 @@ static int __init mvebu_v7_cpu_pm_init(v
 		return 0;
 	of_node_put(np);
 
+	/*
+	 * Currently the CPU idle support for Armada 38x is broken, as
+	 * the CPU hotplug uses some of the CPU idle functions it is
+	 * broken too, so let's disable it
+	 */
+	if (of_machine_is_compatible("marvell,armada380")) {
+		cpu_hotplug_disable();
+		pr_warn("CPU hotplug support is currently broken on Armada 38x: disabling");
+	}
+
 	if (of_machine_is_compatible("marvell,armadaxp"))
 		ret = armada_xp_cpuidle_init();
 	else if (of_machine_is_compatible("marvell,armada370"))
@@ -489,7 +502,8 @@ static int __init mvebu_v7_cpu_pm_init(v
 		return ret;
 
 	mvebu_v7_pmsu_enable_l2_powerdown_onidle();
-	platform_device_register(&mvebu_v7_cpuidle_device);
+	if (mvebu_v7_cpuidle_device.name)
+		platform_device_register(&mvebu_v7_cpuidle_device);
 	cpu_pm_register_notifier(&mvebu_v7_cpu_pm_notifier);
 
 	return 0;


Patches currently in stable-queue which might be from gregory.clement@free-electrons.com are

queue-3.19/arm-dts-dove-fix-uart-reg-property.patch
queue-3.19/arm-mvebu-disable-cpu-idle-on-armada-38x.patch