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

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Date:   Thu, 21 Oct 2021 14:56:47 +0800
From:   Kai-Heng Feng <kai.heng.feng@...onical.com>
To:     Bjorn Helgaas <bhelgaas@...gle.com>
Cc:     Lukas Wunner <lukas@...ner.de>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>,
        "open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] PCI: Check PCIe upstream port for PME support

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...

> ---
> 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
>