target/linux/mvebu/patches-3.18/031-disable_cpu_idle_on_armada_38x.patch

   1 On Armada 38x SoCs, under heavy I/O load, the system hangs when CPU
   2 Idle is enabled. Waiting for a solution to this issue, this patch
   3 disables the CPU Idle support for this SoC.
   4
   5 As CPU Hot plug support also uses some of the CPU Idle functions it is
   6 also affected by the same issue. This patch disables it also for the
   7 Armada 38x SoCs.
   8
   9 Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
  10 Tested-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
  11 Cc: <stable@vger.kernel.org> # v3.17 +
  12 ---
  13 Hi,
  14
  15 In this version I removed the unneeded initialization of the ret
  16 variable, I also fixed the warning message, and finally I added the
  17 Tested-by from Thomas.
  18
  19 Gregory
  20
  21  arch/arm/mach-mvebu/pmsu.c | 16 +++++++++++++++-
  22  1 file changed, 15 insertions(+), 1 deletion(-)
  23
  24 --- a/arch/arm/mach-mvebu/pmsu.c
  25 +++ b/arch/arm/mach-mvebu/pmsu.c
  26 @@ -415,6 +415,9 @@ static __init int armada_38x_cpuidle_ini
  27         void __iomem *mpsoc_base;
  28         u32 reg;
  29
  30 +       pr_warn("CPU idle is currently broken on Armada 38x: disabling");
  31 +       return 0;
  32 +
  33         np = of_find_compatible_node(NULL, NULL,
  34                                      "marvell,armada-380-coherency-fabric");
  35         if (!np)
  36 @@ -476,6 +479,16 @@ static int __init mvebu_v7_cpu_pm_init(v
  37                 return 0;
  38         of_node_put(np);
  39
  40 +       /*
  41 +        * Currently the CPU idle support for Armada 38x is broken, as
  42 +        * the CPU hotplug uses some of the CPU idle functions it is
  43 +        * broken too, so let's disable it
  44 +        */
  45 +       if (of_machine_is_compatible("marvell,armada380")) {
  46 +               cpu_hotplug_disable();
  47 +               pr_warn("CPU hotplug support is currently broken on Armada 38x: disabling");
  48 +       }
  49 +
  50         if (of_machine_is_compatible("marvell,armadaxp"))
  51                 ret = armada_xp_cpuidle_init();
  52         else if (of_machine_is_compatible("marvell,armada370"))
  53 @@ -489,7 +502,8 @@ static int __init mvebu_v7_cpu_pm_init(v
  54                 return ret;
  55
  56         mvebu_v7_pmsu_enable_l2_powerdown_onidle();
  57 -       platform_device_register(&mvebu_v7_cpuidle_device);
  58 +       if (mvebu_v7_cpuidle_device.name)
  59 +               platform_device_register(&mvebu_v7_cpuidle_device);
  60         cpu_pm_register_notifier(&mvebu_v7_cpu_pm_notifier);
  61
  62         return 0;