Re: [PATCH v4 2/2] PCI: Don't assume root ports from > 2015 are power manageable

[Limonciello, Mario]

On 5/25/2023 11:03 AM, Sathyanarayanan Kuppuswamy wrote:
> On 5/24/23 12:07 PM, Mario Limonciello wrote:
>
> This looks like a generic fix to me. So why talk about > 2015? IMO,
> you can remove > 2015 from the title.
The issue was caused by the >2015 heuristic.  If that's taken
out then it went away.  But yes; I agree with you.  If I need
to respin I'll remove this.
> > Using a USB keyboard or mouse to wakeup the system from s2idle fails when
> > that XHCI device is connected to a USB-C port for an AMD USB4 router.
> >
> > Due to commit 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
> > all PCIe ports go into D3 during s2idle.
> >
> > When specific root ports are put into D3 over s2idle on some AMD platforms
> > it is not possible for the platform to properly identify wakeup sources.
> > This happens whether the root port goes into D3hot or D3cold.
> I think Linux/Windows comparison is also not needed. But it is up to you.
I think up to Bjorn :)
> > Comparing registers between Linux and Windows 11 this behavior to put
> > these specific root ports into D3 at suspend is unique to Linux. On an
> > affected system Windows does not put those specific root ports into D3
> > over Modern Standby.
> >
> > Windows doesn't put the root ports into D3 because root ports are not
> > power manageable.
> >
> > Linux shouldn't assume root ports support D3 just because they're on a
> > machine newer than 2015, the ports should also be deemed power manageable.
> > Add an extra check explicitly for root ports to ensure D3 isn't selected
> > for these ports.
> Other than above suggestions, rest looks good to me.
>
> Reviewed-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>
Much appreciated!
> > Fixes: 9d26d3a8f1b0 ("PCI: Put PCIe ports into D3 during suspend")
> > Reported-by: Iain Lane <iain@xxxxxxxxxxxxxxxxxxx>
> > Closes: https://forums.lenovo.com/t5/Ubuntu/Z13-can-t-resume-from-suspend-with-external-USB-keyboard/m-p/5217121
> > Signed-off-by: Mario Limonciello <mario.limonciello@xxxxxxx>
> > ---
> > v3->v4:
> >   * Move after refactor
> > ---
> >   drivers/pci/pci.c | 8 ++++++++
> >   1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > index d1fa040bcea7..d293db963327 100644
> > --- a/drivers/pci/pci.c
> > +++ b/drivers/pci/pci.c
> > @@ -3015,6 +3015,14 @@ bool pci_bridge_d3_possible(struct pci_dev *bridge)
> >   	if (dmi_check_system(bridge_d3_blacklist))
> >   		return false;
> >   
> > +	/*
> > +	 * It's not safe to put root ports that don't support power
> > +	 * management into D3.
> > +	 */
> > +	if (pci_pcie_type(bridge) == PCI_EXP_TYPE_ROOT_PORT &&
> > +	    !platform_pci_power_manageable(bridge))
> > +		return false;
> > +
> >   	/*
> >   	 * It should be safe to put PCIe ports from 2015 or newer
> >   	 * to D3.