| Message ID | 20250514193406.3998101-2-superm1@kernel.org |
|---|---|
| State | New |
| Headers | show |
| Series | Improvements to S5 power consumption | expand |
On Wed, May 14, 2025 at 9:34 PM Mario Limonciello <superm1@kernel.org> wrote: > > From: Mario Limonciello <mario.limonciello@amd.com> > > 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 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." > > 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, modify the PM core to call all the device hibernate > callbacks when turning off the system 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@canonical.com> > Cc: Kai-Heng Feng <kaihengf@nvidia.com> > Cc: Mark Pearson <mpearson-lenovo@squebb.ca> > Cc: Merthan Karakaş <m3rthn.k@gmail.com> > Tested-by: Denis Benato <benato.denis96@gmail.com> > Link: https://lore.kernel.org/linux-pci/20231213182656.6165-1-mario.limonciello@amd.com/ > Link: https://lore.kernel.org/linux-pci/20250506041934.1409302-1-superm1@kernel.org/ > Signed-off-by: Mario Limonciello <mario.limonciello@amd.com> > --- > v2: > * Handle failures to hibernate (fall back to shutdown) > * Don't use dedicated events > * Only allow under CONFIG_HIBERNATE_CALLBACKS > --- > kernel/reboot.c | 12 ++++++++++++ > 1 file changed, 12 insertions(+) > > diff --git a/kernel/reboot.c b/kernel/reboot.c > index ec087827c85cd..52f5e6e36a6f8 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 +306,17 @@ 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_HIBERNATE)) > + goto resume_devices; A failure of one device may trigger a cascade of failures when trying to resume devices and it is not even necessary to resume the ones that have been powered off successfully. IMV this should just ignore errors during the processing of devices, so maybe introduce PMSG_POWEROFF for it? It should also ignore wakeup events that occur while devices are powered off. > + if (dpm_suspend_end(PMSG_HIBERNATE)) > + goto resume_devices; > + return; > + > +resume_devices: > + pr_emerg("Failed to power off devices, using shutdown instead.\n"); > + dpm_resume_end(PMSG_RESTORE); Unfortunately, PMSG_RESTORE is not the right resume action for PMSG_HIBERNATE because it may not power-up things (some drivers assume that the restore kernel will power-up devices and so they don't do it in "restore" callbacks). I do realize that hibernation uses it to reverse PMSG_HIBERNATE, but it should not do that either. That may be fixed later, though. > +#endif > device_shutdown(); > } > /** > -- I'd prefer to get back to this series after the 6.16 merge window starts. It is sort of last minute for 6.16 and it is far from ready IMV. Thanks!
diff --git a/kernel/reboot.c b/kernel/reboot.c index ec087827c85cd..52f5e6e36a6f8 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 +306,17 @@ 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_HIBERNATE)) + goto resume_devices; + if (dpm_suspend_end(PMSG_HIBERNATE)) + goto resume_devices; + return; + +resume_devices: + pr_emerg("Failed to power off devices, using shutdown instead.\n"); + dpm_resume_end(PMSG_RESTORE); +#endif device_shutdown(); } /**