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

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Date:   Thu, 21 Oct 2021 21:13:29 +0200
From:   "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
To:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>
CC:     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 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?

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


>> ---
>> 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
>>