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    SubjectRe: [PATCH v2 2/5] cpu_pm: call notifiers during suspend
    Date
    Santosh Shilimkar <santosh.shilimkar@ti.com> writes:

    > From: Colin Cross <ccross@android.com>
    >
    > Implements syscore_ops in cpu_pm to call the cpu and
    > cpu cluster notifiers during suspend and resume,
    > allowing drivers receiving the notifications to
    > avoid implementing syscore_ops.
    >
    > Signed-off-by: Colin Cross <ccross@android.com>
    > [santosh.shilimkar@ti.com: Rebased against 3.1-rc4]
    > Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>

    I don't think using syscore_ops is right here. The platform code should
    decide where in its own suspend path the notifiers should be triggered.

    The reason is because while the syscore_ops run late in the suspend
    path, they still run before some platform-specific decisions about the
    low-power states are made. That means that any notifiers that need to
    use information about the target low-power state (e.g. whether context
    will be lost or not) cannot do so since that information has not yet
    been decided until the platform_suspend_ops->enter() runs.

    Basically, I think the cpu_*_pm_enter() calls should be called by
    platform-specific code, not by common code.

    Kevin

    > ---
    > kernel/cpu_pm.c | 33 +++++++++++++++++++++++++++++++++
    > 1 files changed, 33 insertions(+), 0 deletions(-)
    >
    > diff --git a/kernel/cpu_pm.c b/kernel/cpu_pm.c
    > index 54aa892..3d115d0 100644
    > --- a/kernel/cpu_pm.c
    > +++ b/kernel/cpu_pm.c
    > @@ -20,6 +20,7 @@
    > #include <linux/module.h>
    > #include <linux/notifier.h>
    > #include <linux/spinlock.h>
    > +#include <linux/syscore_ops.h>
    >
    > static DEFINE_RWLOCK(cpu_pm_notifier_lock);
    > static RAW_NOTIFIER_HEAD(cpu_pm_notifier_chain);
    > @@ -113,3 +114,35 @@ int cpu_cluster_pm_exit(void)
    > return ret;
    > }
    > EXPORT_SYMBOL_GPL(cpu_cluster_pm_exit);
    > +
    > +#ifdef CONFIG_PM
    > +static int cpu_pm_suspend(void)
    > +{
    > + int ret;
    > +
    > + ret = cpu_pm_enter();
    > + if (ret)
    > + return ret;
    > +
    > + ret = cpu_cluster_pm_enter();
    > + return ret;
    > +}
    > +
    > +static void cpu_pm_resume(void)
    > +{
    > + cpu_cluster_pm_exit();
    > + cpu_pm_exit();
    > +}
    > +
    > +static struct syscore_ops cpu_pm_syscore_ops = {
    > + .suspend = cpu_pm_suspend,
    > + .resume = cpu_pm_resume,
    > +};
    > +
    > +static int cpu_pm_init(void)
    > +{
    > + register_syscore_ops(&cpu_pm_syscore_ops);
    > + return 0;
    > +}
    > +core_initcall(cpu_pm_init);
    > +#endif


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