Suspend-to-idle (aka the "freeze" sleep state) is a system sleep state in which all of the processors enter deepest possible idle state and wait for interrupts right after suspending all the devices.
There is no hard requirement for a platform to support and register platform specific suspend_ops to enter suspend-to-idle/freeze state. Only deeper system sleep states like PM_SUSPEND_STANDBY and PM_SUSPEND_MEM rely on such low level support/implementation. suspend-to-idle can be entered as along as all the devices can be suspended. This patch enables the support for suspend-to-idle even on systems that don't have any low level support for deeper system sleep states and/or don't register any platform specific suspend_ops. Cc: "Rafael J. Wysocki" <[email protected]> Signed-off-by: Sudeep Holla <[email protected]> --- kernel/power/main.c | 5 +++++ kernel/power/suspend.c | 8 +++++--- 2 files changed, 10 insertions(+), 3 deletions(-) Hi Rafael, I am not sure if you like this approach. I found this to be the simplest but I may have missed to consider all possible corner cases especially for x86 and other platforms. I don't see any such issues/cases with ARM systems. Regards, Sudeep diff --git a/kernel/power/main.c b/kernel/power/main.c index 5ea50b1b7595..0f0fd9184f39 100644 --- a/kernel/power/main.c +++ b/kernel/power/main.c @@ -651,6 +651,11 @@ static int __init pm_init(void) if (error) return error; pm_print_times_init(); + /* + * freeze state should be supported even without any suspend_ops, + * calling suspend_set_ops without any ops will setup freeze state + */ + suspend_set_ops(NULL); return pm_autosleep_init(); } diff --git a/kernel/power/suspend.c b/kernel/power/suspend.c index 0acab9d7f96f..37d64f811ecd 100644 --- a/kernel/power/suspend.c +++ b/kernel/power/suspend.c @@ -138,7 +138,9 @@ void suspend_set_ops(const struct platform_suspend_ops *ops) lock_system_sleep(); - suspend_ops = ops; + WARN_ONCE(ops && suspend_ops, "overriding suspend_ops"); + if (ops) + suspend_ops = ops; for (i = PM_SUSPEND_MEM; i >= PM_SUSPEND_STANDBY; i--) if (valid_state(i)) { pm_states[i] = pm_labels[j++]; @@ -211,7 +213,7 @@ static int platform_suspend_begin(suspend_state_t state) { if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->begin) return freeze_ops->begin(); - else if (suspend_ops->begin) + else if (suspend_ops && suspend_ops->begin) return suspend_ops->begin(state); else return 0; @@ -221,7 +223,7 @@ static void platform_resume_end(suspend_state_t state) { if (state == PM_SUSPEND_FREEZE && freeze_ops && freeze_ops->end) freeze_ops->end(); - else if (suspend_ops->end) + else if (suspend_ops && suspend_ops->end) suspend_ops->end(); } -- 2.7.4
