On 29.08.2022 16:12, Rafael J. Wysocki wrote: > On Mon, Aug 29, 2022 at 12:21 PM Marek Maślanka <mm@xxxxxxxxxxxx> wrote: >> >> The GPE interrupts that are the wake-up source are "turned off" by clear >> the “enable_for_wake” flag when the kernel resumes (suspend_enter() -> >> acpi_s2idle_restore() -> acpi_disable_wakeup_devices() -> >> acpi_set_gpe_wake_mask()). On the resume path the kernel also resumes >> the interrupts (suspend_enter() -> dpm_resume_noirq() -> resume_irqs()) >> which process the GPE interrupt that woke-up the kernel (... -> >> acpi_irq() -> acpi_ev_sci_xrupt_handler() -> acpi_ev_gpe_detect() -> …). >> The GPE interrupt routine stops in the acpi_ev_gpe_detect () function >> when the "enable_for_wake" flag is cleared. >> >> As the interrupt servicing might work simultaneously on SMP, it’s >> possible that the “enable_for_wake” flag can be cleared before the GPE >> interrupt gets chances to be processed. It might happen when the CPU >> processed other IRQ before the GPE IRQ that woke up the device. >> >> This issue is seen on low-end Chromebooks with two cores CPU when HPET >> IRQ is triggered while resuming the device and is processed before the >> ACPI GPE interrupt on the same CPU core. >> >> Before clear the enable_for_wake flag we need to make sure that the >> specific wake-up GPE IRQ block was processed. >> >> Signed-off-by: Marek Maslanka <mm@xxxxxxxxxxxx> > > First off, if you want to modify ACPICA code, the way to do that is > via the upstream ACPICA project on GitHub. > > Second, I'm not sure what the problem is. > > Yes, acpi_ev_gpe_detect() will bail out early when none of the GPEs in > the given block is enabled either for wake or for run, but since the > system has been woken up already and the GPE is now disabled, it will > not trigger again until enabled next time. > > Is the problem that the GPE will signal wakeup spuriously on the next > suspend or is it something else? In my cases the problem is the GPE STS flag that cannot be cleared (acpi_ev_gpe_detect() -> acpi_ev_detect_gpe() -> acpi_ev_gpe_dispatch() -> acpi_hw_clear_gpe()). If the status bit is not cleared before the next suspend, the device will not wake up.
