* PME while runtime suspend
@ 2021-02-26 10:37 Loic Poulain
2021-02-26 22:22 ` Bjorn Helgaas
0 siblings, 1 reply; 4+ messages in thread
From: Loic Poulain @ 2021-02-26 10:37 UTC (permalink / raw)
To: Bjorn Helgaas; +Cc: linux-pci
Hi Bjorn,
Trying to support runtime suspend in a driver, which puts the device
in D3hot and wait either for host/driver initiated resume
(runtime_get), or device initiated resume (PME).
But, given that old change: 42eca2302146 ("PCI: Don't touch card regs
after runtime suspend D3")
PME that was enabled from pci_finish_runtime_suspend() is not enabled
anymore for almost all drivers in case of runtime-suspend. The only
way to enable this is by calling pci_wake_from_d3() from the PCI device
driver's runtime_suspend() callback, but this function fails if the
device wake_up is not enabled, which makes sense since it targets
system-wide sleep wake-up (and wake-up is user/distro policy).
So is there a proper way to allow PME while the device is runtime
suspended, without having to tell the user to enabled 'unrelated' wake_up
capability?
Regards,
Loic
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: PME while runtime suspend 2021-02-26 10:37 PME while runtime suspend Loic Poulain @ 2021-02-26 22:22 ` Bjorn Helgaas 2021-03-02 14:52 ` Loic Poulain 0 siblings, 1 reply; 4+ messages in thread From: Bjorn Helgaas @ 2021-02-26 22:22 UTC (permalink / raw) To: Loic Poulain Cc: Bjorn Helgaas, linux-pci, Dave Airlie, Rafael J. Wysocki, Vaibhav Gupta, linux-pm [+cc Rafael, Dave (author of 42eca2302146), Vaibhav, linux-pm] On Fri, Feb 26, 2021 at 11:37:12AM +0100, Loic Poulain wrote: > Hi Bjorn, > > Trying to support runtime suspend in a driver, which puts the device > in D3hot and wait either for host/driver initiated resume > (runtime_get), or device initiated resume (PME). > > But, given that old change: 42eca2302146 ("PCI: Don't touch card regs > after runtime suspend D3") > > PME that was enabled from pci_finish_runtime_suspend() is not enabled > anymore for almost all drivers in case of runtime-suspend. The only > way to enable this is by calling pci_wake_from_d3() from the PCI device > driver's runtime_suspend() callback, but this function fails if the > device wake_up is not enabled, which makes sense since it targets > system-wide sleep wake-up (and wake-up is user/distro policy). > > So is there a proper way to allow PME while the device is runtime > suspended, without having to tell the user to enabled 'unrelated' wake_up > capability? pci_pm_runtime_suspend() calls pci_finish_runtime_suspend(), which enables wake-up, unless "pci_dev->state_saved". IIUC we should be enabling wake-up unless the driver has called pci_save_state() itself. So I infer that your driver does call pci_save_state() and the PCI core does not enable wake-up. Right? Why does your driver call pci_save_state()? In most cases I don't think drivers should need to do that themselves because the PCI core will do it for them. E.g., see Vaibhav's recent eb6779d4c505 ("e1000: use generic power management") [1] Bjorn [1] https://git.kernel.org/linus/eb6779d4c505 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: PME while runtime suspend 2021-02-26 22:22 ` Bjorn Helgaas @ 2021-03-02 14:52 ` Loic Poulain 2021-03-02 16:32 ` Bjorn Helgaas 0 siblings, 1 reply; 4+ messages in thread From: Loic Poulain @ 2021-03-02 14:52 UTC (permalink / raw) To: Bjorn Helgaas Cc: Bjorn Helgaas, linux-pci, Dave Airlie, Rafael J. Wysocki, Vaibhav Gupta, open list:QUALCOMM CPUFREQ DRIVER MSM8996/APQ8096 Hi Bjorn, On Fri, 26 Feb 2021 at 23:22, Bjorn Helgaas <helgaas@kernel.org> wrote: > > [+cc Rafael, Dave (author of 42eca2302146), Vaibhav, linux-pm] > > On Fri, Feb 26, 2021 at 11:37:12AM +0100, Loic Poulain wrote: > > Hi Bjorn, > > > > Trying to support runtime suspend in a driver, which puts the device > > in D3hot and wait either for host/driver initiated resume > > (runtime_get), or device initiated resume (PME). > > > > But, given that old change: 42eca2302146 ("PCI: Don't touch card regs > > after runtime suspend D3") > > > > PME that was enabled from pci_finish_runtime_suspend() is not enabled > > anymore for almost all drivers in case of runtime-suspend. The only > > way to enable this is by calling pci_wake_from_d3() from the PCI device > > driver's runtime_suspend() callback, but this function fails if the > > device wake_up is not enabled, which makes sense since it targets > > system-wide sleep wake-up (and wake-up is user/distro policy). > > > > So is there a proper way to allow PME while the device is runtime > > suspended, without having to tell the user to enabled 'unrelated' wake_up > > capability? > > pci_pm_runtime_suspend() calls pci_finish_runtime_suspend(), which > enables wake-up, unless "pci_dev->state_saved". IIUC we should be > enabling wake-up unless the driver has called pci_save_state() itself. > > So I infer that your driver does call pci_save_state() and the PCI > core does not enable wake-up. Right? Right. > > Why does your driver call pci_save_state()? In most cases I don't > think drivers should need to do that themselves because the PCI core > will do it for them. E.g., see Vaibhav's recent eb6779d4c505 ("e1000: > use generic power management") [1] Thanks for the pointer, I was storing the PCI state in order to restore it when the device is crashing and lose its PCI context. But I can do that one time once the device is initialized. I've applied the same changes as you pointed, and it works as expected. Thanks, Loic ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: PME while runtime suspend 2021-03-02 14:52 ` Loic Poulain @ 2021-03-02 16:32 ` Bjorn Helgaas 0 siblings, 0 replies; 4+ messages in thread From: Bjorn Helgaas @ 2021-03-02 16:32 UTC (permalink / raw) To: Loic Poulain Cc: Bjorn Helgaas, linux-pci, Dave Airlie, Rafael J. Wysocki, Vaibhav Gupta, open list:QUALCOMM CPUFREQ DRIVER MSM8996/APQ8096 On Tue, Mar 02, 2021 at 03:52:05PM +0100, Loic Poulain wrote: > Hi Bjorn, > > On Fri, 26 Feb 2021 at 23:22, Bjorn Helgaas <helgaas@kernel.org> wrote: > > > > [+cc Rafael, Dave (author of 42eca2302146), Vaibhav, linux-pm] > > > > On Fri, Feb 26, 2021 at 11:37:12AM +0100, Loic Poulain wrote: > > > Hi Bjorn, > > > > > > Trying to support runtime suspend in a driver, which puts the device > > > in D3hot and wait either for host/driver initiated resume > > > (runtime_get), or device initiated resume (PME). > > > > > > But, given that old change: 42eca2302146 ("PCI: Don't touch card regs > > > after runtime suspend D3") > > > > > > PME that was enabled from pci_finish_runtime_suspend() is not enabled > > > anymore for almost all drivers in case of runtime-suspend. The only > > > way to enable this is by calling pci_wake_from_d3() from the PCI device > > > driver's runtime_suspend() callback, but this function fails if the > > > device wake_up is not enabled, which makes sense since it targets > > > system-wide sleep wake-up (and wake-up is user/distro policy). > > > > > > So is there a proper way to allow PME while the device is runtime > > > suspended, without having to tell the user to enabled 'unrelated' wake_up > > > capability? > > > > pci_pm_runtime_suspend() calls pci_finish_runtime_suspend(), which > > enables wake-up, unless "pci_dev->state_saved". IIUC we should be > > enabling wake-up unless the driver has called pci_save_state() itself. > > > > So I infer that your driver does call pci_save_state() and the PCI > > core does not enable wake-up. Right? > > Right. > > > Why does your driver call pci_save_state()? In most cases I don't > > think drivers should need to do that themselves because the PCI core > > will do it for them. E.g., see Vaibhav's recent eb6779d4c505 ("e1000: > > use generic power management") [1] > > Thanks for the pointer, I was storing the PCI state in order to > restore it when the device is crashing and lose its PCI context. But I > can do that one time once the device is initialized. I've applied the > same changes as you pointed, and it works as expected. Great, thanks for letting us know! It's always nice when you can *remove* code and things work better! Bjorn ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2021-03-03 2:02 UTC | newest] Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-02-26 10:37 PME while runtime suspend Loic Poulain 2021-02-26 22:22 ` Bjorn Helgaas 2021-03-02 14:52 ` Loic Poulain 2021-03-02 16:32 ` Bjorn Helgaas
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