On Wed, Apr 08, 2015 at 11:54:38AM +0100, Tomeu Vizoso wrote:
> This callback is expected to do the same as enter() only that all
> non-wakeup IRQs are expected to be disabled.
This is not true or at least it is misworded. The enter_freeze() function
is expected to return from the state with IRQs disabled at CPU level, or
put it differently it must not re-enable IRQs while executing since the
tick is frozen.
> It will be called when the system goes to suspend-to-idle and will
> reduce power usage because CPUs won't be awaken for unnecessary IRQs.
>
> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> arch/arm/mach-tegra/cpuidle-tegra114.c | 31 ++++++++++++++++++++++++-------
> 1 file changed, 24 insertions(+), 7 deletions(-)
>
> diff --git a/arch/arm/mach-tegra/cpuidle-tegra114.c b/arch/arm/mach-tegra/cpuidle-tegra114.c
> index f2b586d..ef06001 100644
> --- a/arch/arm/mach-tegra/cpuidle-tegra114.c
> +++ b/arch/arm/mach-tegra/cpuidle-tegra114.c
> @@ -39,28 +39,44 @@ static int tegra114_idle_power_down(struct cpuidle_device *dev,
> struct cpuidle_driver *drv,
> int index)
> {
> - local_fiq_disable();
> -
> tegra_set_cpu_in_lp2();
> cpu_pm_enter();
>
> - clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
> -
> call_firmware_op(prepare_idle);
>
> /* Do suspend by ourselves if the firmware does not implement it */
> if (call_firmware_op(do_idle, 0) == -ENOSYS)
> cpu_suspend(0, tegra30_sleep_cpu_secondary_finish);
>
> - clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
> -
> cpu_pm_exit();
> tegra_clear_cpu_in_lp2();
>
> + return index;
> +}
> +
> +static int tegra114_idle_enter(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index)
> +{
> + local_fiq_disable();
> +
> + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER, &dev->cpu);
> +
> + index = tegra114_idle_power_down(dev, drv, index);
> +
> + clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT, &dev->cpu);
> +
> local_fiq_enable();
>
> return index;
> }
> +
> +static void tegra114_idle_enter_freeze(struct cpuidle_device *dev,
> + struct cpuidle_driver *drv,
> + int index)
> +{
> + tegra114_idle_power_down(dev, drv, index);
Cool. So if the problem is FIQs, you don't disabled them on entry
which means you enter the "frozen" state with FIQs enabled and tick frozen,
unless I am missing something.
The question here is: are we allowed to enable FIQs before returning
from an enter_freeze() call (and to enter it with FIQs enabled) ?
If we are not your code here certainly does not solve the issue, since
it does _not_ disable FIQs upon enter_freeze call anyway.
Lorenzo
> +}
> #endif
>
> static struct cpuidle_driver tegra_idle_driver = {
> @@ -71,7 +87,8 @@ static struct cpuidle_driver tegra_idle_driver = {
> [0] = ARM_CPUIDLE_WFI_STATE_PWR(600),
> #ifdef CONFIG_PM_SLEEP
> [1] = {
> - .enter = tegra114_idle_power_down,
> + .enter = tegra114_idle_enter,
> + .enter_freeze = tegra114_idle_enter_freeze,
> .exit_latency = 500,
> .target_residency = 1000,
> .power_usage = 0,
> --
> 2.3.4
>
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