Re: [PATCH v2] PCI / PM: Always check PME wakeup capability for runtime wakeup support

[Kai-Heng Feng]

Rafael J. Wysocki <rjw@xxxxxxxxxxxxx> wrote:

> On Monday, March 26, 2018 7:54:35 AM CEST Kai Heng Feng wrote:
> > Hi Bjorn, Rafael,
> >
> > > On Mar 19, 2018, at 10:09 PM, Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> > > wrote:
> > >
> > > USB controller ASM1042 stops working after commit de3ef1eb1cd0 ("PM /
> > > core: Drop run_wake flag from struct dev_pm_info").
> > >
> > > The device in question is not power managed by platform firmware,
> > > furthermore, it only supports PME# from D3cold:
> > > Capabilities: [78] Power Management version 3
> > >        Flags: PMEClk- DSI- D1- D2- AuxCurrent=55mA PME(D0-,D1-,D2-,D3hot-,D3cold+)
> > >        Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
> > >
> > > Before commit de3ef1eb1cd0, the device never gets runtime suspended.
> > > After that commit, the device gets runtime suspended, so it does not
> > > respond to any PME#.
> > >
> > > usb_hcd_pci_probe() mandatorily calls device_wakeup_enable(), hence
> > > device_can_wakeup() in pci_dev_run_wake() always returns true.
> > >
> > > So pci_dev_run_wake() needs to check PME wakeup capability as its first
> > > condition.
> > >
> > > Fixes: de3ef1eb1cd0 ("PM / core: Drop run_wake flag from struct
> > > dev_pm_info")
> > > Cc: stable@xxxxxxxxxxxxxxx # 4.13+
> > > Signed-off-by: Kai-Heng Feng <kai.heng.feng@xxxxxxxxxxxxx>
> >
> >
> > Is there any improvement I can address?
> > Or do you have any concern about this patch?
> >
> > Kai-Heng
> >
> > > ---
> > > v2: Explicitly check dev->pme_support.
> > >
> > >  drivers/pci/pci.c | 8 ++++----
> > >  1 file changed, 4 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> > > index f6a4dd10d9b0..52821a21fc07 100644
> > > --- a/drivers/pci/pci.c
> > > +++ b/drivers/pci/pci.c
> > > @@ -2125,16 +2125,16 @@ bool pci_dev_run_wake(struct pci_dev *dev)
> > >  {
> > >  	struct pci_bus *bus = dev->bus;
> > >
> > > -	if (device_can_wakeup(&dev->dev))
> > > -		return true;
> > > -
> > >  	if (!dev->pme_support)
> > >  		return false;
> > >
> > >  	/* PME-capable in principle, but not from the target power state */
> > > -	if (!pci_pme_capable(dev, pci_target_state(dev, false)))
> > > +	if (!pci_pme_capable(dev, pci_target_state(dev, true)))
>
> So why do you change 'false' to 'true' here?
>
> At least that change should be mentioned in the changelog too.

I'll update the reason in the change log.

Thanks.

> > > return false;
> > >
> > > +	if (device_can_wakeup(&dev->dev))
> > > +		return true;
> > > +
> > >  	while (bus->parent) {
> > >  		struct pci_dev *bridge = bus->self;