On Wed, May 24, 2023 at 6:16 PM Limonciello, Mario
<Mario.Limonciello@xxxxxxx> wrote:
>
> [AMD Official Use Only - General]
>
> > -----Original Message-----
> > From: Lukas Wunner <lukas@xxxxxxxxx>
> > Sent: Wednesday, May 24, 2023 10:45 AM
> > To: Limonciello, Mario <Mario.Limonciello@xxxxxxx>
> > Cc: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>; Mika Westerberg
> > <mika.westerberg@xxxxxxxxxxxxxxx>; Rafael J . Wysocki <rafael@xxxxxxxxxx>;
> > linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; S-k, Shyam-sundar
> > <Shyam-sundar.S-k@xxxxxxx>; Natikar, Basavaraj
> > <Basavaraj.Natikar@xxxxxxx>; Deucher, Alexander
> > <Alexander.Deucher@xxxxxxx>; linux-pm@xxxxxxxxxxxxxxx; Iain Lane
> > <iain@xxxxxxxxxxxxxxxxxxx>
> > Subject: Re: [PATCH v3] PCI: Don't assume root ports from > 2015 are power
> > manageable
> >
> > On Wed, May 24, 2023 at 10:21:36AM -0500, Mario Limonciello wrote:
> > > --- a/drivers/pci/pci.c
> > > +++ b/drivers/pci/pci.c
> > > @@ -2976,6 +2976,9 @@ bool pci_bridge_d3_possible(struct pci_dev
> > *bridge)
> > >
> > > switch (pci_pcie_type(bridge)) {
> > > case PCI_EXP_TYPE_ROOT_PORT:
> > > + if (!platform_pci_power_manageable(bridge))
> > > + return false;
> > > + fallthrough;
> > > case PCI_EXP_TYPE_UPSTREAM:
> > > case PCI_EXP_TYPE_DOWNSTREAM:
> > > if (pci_bridge_d3_disable)
> >
> > This will exempt the Root Ports from pcie_port_pm=force.
> > Not sure if that's desirable.
>
> Right; It will only exempt root ports from pcie_port_pm=force
> if they aren't power manageable.
>
> If it's still desirable to let pcie_port_pm=force work on these
> I think it's worth refactoring the function otherwise it's going
> to be a nested if that matches the same variable as the
> switch.
>
> Something like this:
>
> bool pci_bridge_d3_possible(struct pci_dev *bridge)
> {
> if (!pci_is_pcie(bridge))
> return false;
>
> switch (pci_pcie_type(bridge)) {
> case PCI_EXP_TYPE_ROOT_PORT:
> case PCI_EXP_TYPE_UPSTREAM:
> case PCI_EXP_TYPE_DOWNSTREAM:
> break;
> default:
> return false;
> }
>
> if (pci_bridge_d3_disable)
> return false;
>
> /*
> * Hotplug ports handled by firmware in System Management Mode
> * may not be put into D3 by the OS (Thunderbolt on non-Macs).
> */
> if (bridge->is_hotplug_bridge && !pciehp_is_native(bridge))
> return false;
>
> if (pci_bridge_d3_force)
> return true;
>
> /* Even the oldest 2010 Thunderbolt controller supports D3. */
> if (bridge->is_thunderbolt)
> return true;
>
> /* Platform might know better if the bridge supports D3 */
> if (platform_pci_bridge_d3(bridge))
> return true;
>
> /*
> * Hotplug ports handled natively by the OS were not validated
> * by vendors for runtime D3 at least until 2018 because there
> * was no OS support.
> */
> if (bridge->is_hotplug_bridge)
> return false;
>
> if (dmi_check_system(bridge_d3_blacklist))
> return false;
>
> /*
> * It should be safe to put PCIe ports from 2015 or newer
> * to D3.
> */
> if (dmi_get_bios_year() >= 2015)
> return true;
>
> return false;
> }
>
> Then the check I'm proposing can injected anywhere after the force like this:
>
> if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT &&
> !platform_pci_power_manageable(bridge)))
> return false;
Sounds reasonable. I would even put it after the Thunderbolt check.
