linux-kernel - Re: [PATCH v2] PCI: Check PCIe upstream port for PME support

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Message-ID: <CAAd53p5ZUDjjaWPHE4p1vg=3LzcCovngdS8VO0uFuVanEtAAYg@mail.gmail.com>
Date:   Fri, 22 Oct 2021 11:04:44 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Lukas Wunner <lukas@...ner.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [PATCH v2] PCI: Check PCIe upstream port for PME support

On Fri, Oct 22, 2021 at 3:13 AM Rafael J. Wysocki
<rafael.j.wysocki@...el.com> wrote:
>
> On 10/21/2021 8:56 AM, Kai-Heng Feng wrote:
> > On Thu, Aug 12, 2021 at 11:39 PM Kai-Heng Feng
> > <kai.heng.feng@...onical.com> wrote:
> >> Some platforms cannot detect ethernet hotplug once its upstream port is
> >> runtime suspended because PME isn't granted by BIOS _OSC. The issue can
> >> be workarounded by "pcie_ports=native".
> >>
> >> The vendor confirmed that the PME in _OSC is disabled intentionally for
> >> system stability issues on the other OS, so we should also honor the PME
> >> setting here.
> >>
> >> So before marking PME support status for the device, check
> >> PCI_EXP_RTCTL_PMEIE bit to ensure PME interrupt is either enabled by
> >> firmware or OS.
> >>
> >> Cc: Lukas Wunner <lukas@...ner.de>
> >> Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>
> >> Cc: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >> Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=213873
> >> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> > A gentle ping...
>
> Any chance to CC this to linux-pm too?

Will remember this next time.

>
> So you basically want to check whether or not the PME interrupts are
> configured on the port?

Yes, that's the idea here.

Kai-Heng

>
>
> >> ---
> >> v2:
> >>   - Instead of prevent root port from runtime suspending, skip
> >>     initializing PME status for the downstream device.
> >>
> >>   drivers/pci/pci.c | 28 +++++++++++++++++++++++++++-
> >>   1 file changed, 27 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> >> index aacf575c15cf..4344dc302edd 100644
> >> --- a/drivers/pci/pci.c
> >> +++ b/drivers/pci/pci.c
> >> @@ -2294,6 +2294,32 @@ void pci_pme_wakeup_bus(struct pci_bus *bus)
> >>                  pci_walk_bus(bus, pci_pme_wakeup, (void *)true);
> >>   }
> >>
> >> +#ifdef CONFIG_PCIE_PME
> >> +static bool pci_pcie_port_pme_enabled(struct pci_dev *dev)
> >> +{
> >> +       struct pci_dev *bridge = pci_upstream_bridge(dev);
> >> +       u16 val;
> >> +       int ret;
> >> +
> >> +       if (!bridge)
> >> +               return true;
> >> +
> >> +       if (pci_pcie_type(bridge) != PCI_EXP_TYPE_ROOT_PORT &&
> >> +           pci_pcie_type(bridge) != PCI_EXP_TYPE_RC_EC)
> >> +               return true;
> >> +
> >> +       ret = pcie_capability_read_word(bridge, PCI_EXP_RTCTL, &val);
> >> +       if (ret)
> >> +               return false;
> >> +
> >> +       return val & PCI_EXP_RTCTL_PMEIE;
> >> +}
> >> +#else
> >> +static bool pci_pcie_port_pme_enabled(struct pci_dev *dev)
> >> +{
> >> +       return true;
> >> +}
> >> +#endif
> >>
> >>   /**
> >>    * pci_pme_capable - check the capability of PCI device to generate PME#
> >> @@ -3095,7 +3121,7 @@ void pci_pm_init(struct pci_dev *dev)
> >>          }
> >>
> >>          pmc &= PCI_PM_CAP_PME_MASK;
> >> -       if (pmc) {
> >> +       if (pmc && pci_pcie_port_pme_enabled(dev)) {
> >>                  pci_info(dev, "PME# supported from%s%s%s%s%s\n",
> >>                           (pmc & PCI_PM_CAP_PME_D0) ? " D0" : "",
> >>                           (pmc & PCI_PM_CAP_PME_D1) ? " D1" : "",
> >> --
> >> 2.32.0
> >>
>