On Tue, Sep 09, 2025 at 02:16:18PM -0500, Mario Limonciello (AMD) wrote: > When the system is powered off the kernel will call device_shutdown() > which will issue callbacks into PCI core to wake up a device and call > it's shutdown() callback. This will leave devices in ACPI D0 which can > cause some devices to misbehave with spurious wakeups and also leave some > devices on which will consume power needlessly. The connection between this change and spurious wakeups seems pretty tenuous. If we don't want wakeups, powering off the device seems like a sledgehammer approach. s/it's/its/ > The issue won't happen if the device is in D3 before system shutdown, so > putting device to low power state before shutdown solves the issue. > > ACPI Spec 6.5, "7.4.2.5 System \_S4 State" says "Devices states are > compatible with the current Power Resource states. In other words, all > devices are in the D3 state when the system state is S4." Re patch 05/12, also interesting that this section mentions "devices that are enabled to wake the system and that can do so from their device state in S4 can initiate a hardware event that transitions the system state to S0." So it looks like wakeup from S4 should work in at least some cases. > The following "7.4.2.6 System \_S5 State (Soft Off)" states "The S5 > state is similar to the S4 state except that OSPM does not save any > context." so it's safe to assume devices should be at D3 for S5. > > To accomplish this, use the PMSG_POWEROFF event to call all the device > hibernate callbacks when the kernel is compiled with hibernate support. > If compiled without hibernate support or hibernate fails fall back into > the previous shutdown flow. > > Cc: AceLan Kao <acelan.kao@xxxxxxxxxxxxx> > Cc: Kai-Heng Feng <kaihengf@xxxxxxxxxx> > Cc: Mark Pearson <mpearson-lenovo@xxxxxxxxx> > Cc: Merthan Karakaş <m3rthn.k@xxxxxxxxx> > Tested-by: Eric Naim <dnaim@xxxxxxxxxxx> > Tested-by: Denis Benato <benato.denis96@xxxxxxxxx> > Link: https://lore.kernel.org/linux-pci/20231213182656.6165-1-mario.limonciello@xxxxxxx/ > Link: https://lore.kernel.org/linux-pci/20250506041934.1409302-1-superm1@xxxxxxxxxx/ > Signed-off-by: Mario Limonciello (AMD) <superm1@xxxxxxxxxx> > --- > v5: > * split to multiple commits, re-order > v4: > * https://lore.kernel.org/linux-pci/20250616175019.3471583-1-superm1@xxxxxxxxxx/ > v3: > * Add new PMSG_POWEROFF and PM_EVENT_POWEROFF which alias to poweroff > callbacks > * Don't try to cleanup on dpm_suspend_start() or dpm_suspend_end() failures > Jump right into normal shutdown flow instead. > * https://lore.kernel.org/linux-pm/20250609024619.407257-1-superm1@xxxxxxxxxx/T/#me6db0fb946e3d604a8f3d455128844ed802c82bb > --- > kernel/reboot.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/kernel/reboot.c b/kernel/reboot.c > index ec087827c85cd..c8835f8e5f271 100644 > --- a/kernel/reboot.c > +++ b/kernel/reboot.c > @@ -13,6 +13,7 @@ > #include <linux/kexec.h> > #include <linux/kmod.h> > #include <linux/kmsg_dump.h> > +#include <linux/pm.h> > #include <linux/reboot.h> > #include <linux/suspend.h> > #include <linux/syscalls.h> > @@ -305,6 +306,11 @@ static void kernel_shutdown_prepare(enum system_states state) > (state == SYSTEM_HALT) ? SYS_HALT : SYS_POWER_OFF, NULL); > system_state = state; > usermodehelper_disable(); > +#ifdef CONFIG_HIBERNATE_CALLBACKS > + if (!dpm_suspend_start(PMSG_POWEROFF) && !dpm_suspend_end(PMSG_POWEROFF)) > + return; > + pr_emerg("Failed to power off devices, using shutdown instead.\n"); > +#endif > device_shutdown(); > } > /** > -- > 2.43.0 >
