From: Bjorn Helgaas <helgaas@kernel.org>
To: Loic Poulain <loic.poulain@linaro.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
linux-pci@vger.kernel.org, Dave Airlie <airlied@redhat.com>,
"Rafael J. Wysocki" <rjw@rjwysocki.net>,
Vaibhav Gupta <vaibhavgupta40@gmail.com>,
linux-pm@vger.kernel.org
Subject: Re: PME while runtime suspend
Date: Fri, 26 Feb 2021 16:22:25 -0600 [thread overview]
Message-ID: <20210226222225.GA164608@bjorn-Precision-5520> (raw)
In-Reply-To: <CAMZdPi9PGWcPOHKk3cNU3Nw+hdVOsivLeXzqyd2FQ7nn8dDfvg@mail.gmail.com>
[+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
next prev parent reply other threads:[~2021-02-26 22:23 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-26 10:37 PME while runtime suspend Loic Poulain
2021-02-26 22:22 ` Bjorn Helgaas [this message]
2021-03-02 14:52 ` Loic Poulain
2021-03-02 16:32 ` Bjorn Helgaas
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