lkml.org 
[lkml]   [2023]   [May]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH v3] PCI: Don't assume root ports from > 2015 are power manageable
Date
[AMD Official Use Only - General]

> -----Original Message-----
> From: Lukas Wunner <lukas@wunner.de>
> Sent: Wednesday, May 24, 2023 10:45 AM
> To: Limonciello, Mario <Mario.Limonciello@amd.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>; Mika Westerberg
> <mika.westerberg@linux.intel.com>; Rafael J . Wysocki <rafael@kernel.org>;
> linux-pci@vger.kernel.org; linux-kernel@vger.kernel.org; S-k, Shyam-sundar
> <Shyam-sundar.S-k@amd.com>; Natikar, Basavaraj
> <Basavaraj.Natikar@amd.com>; Deucher, Alexander
> <Alexander.Deucher@amd.com>; linux-pm@vger.kernel.org; Iain Lane
> <iain@orangesquash.org.uk>
> 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;

\
 
 \ /
  Last update: 2023-05-24 18:17    [W:0.529 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site