On 11/1/2022 12:37, Sven van Ashbrook wrote:
On Mon, Oct 31, 2022 at 4:43 PM Mario Limonciello <mario.limonciello@xxxxxxx> wrote:+void pm_set_hw_deepest_state(u64 duration) +{ + suspend_stats.last_hw_deepest_state = duration;I'm wondering if we could add a userspace notification here. Then userspace wouldn't have to synchronize with the suspend/resume state of the system when reading this entry. What about sysfs_notify() ? Or via udev?
The question I would have is what kobj would you notify? power_kobj? Lots of other things write to suspend stats, but nothing else sends notifications. So why is this one going to be special?
To me I don't think it's much different for userspace to "always" read the file after resume vs wait for the notification and then read it.
To make userspace flexible to multiple kernel versions it seems to me that userspace could check if that file exists before suspend and if it does then check the value after suspend.
+} +EXPORT_SYMBOL_GPL(pm_set_hw_deepest_state);
