[+cc Rafael, linux-pm] On Tue, Jun 13, 2017 at 12:21:15PM +0800, Kai-Heng Feng wrote: > On Mon, Jun 12, 2017 at 10:18 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > > Let's get some help from people who understand PCI well. > > > > Here's the general problem: Kai-Heng has a PCI-based USB host > > controller that advertises wakeup capability from D3, but it doesn't > > assert PME# from D3 when it should. For "lspci -vv" output, see > > > > http://marc.info/?l=linux-usb&m=149570231732519&w=2 > > > > On Mon, 12 Jun 2017, Kai-Heng Feng wrote: > > > >> On Mon, Jun 12, 2017 at 3:04 PM, Kai-Heng Feng > >> <kai.heng.feng@xxxxxxxxxxxxx> wrote: > >> > On Fri, Jun 9, 2017 at 10:43 PM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > >> >> On Fri, 9 Jun 2017, Kai-Heng Feng wrote: > >> >> > >> >> Is this really the right solution? Maybe it would be better to allow > >> >> the controller to go into D3 provided no wakeup signal is needed. You > >> >> could do: > >> >> > >> >> device_set_wakeup_capable(&pdev->dev, 0); > >> > > >> > This doesn't work. > >> > After applying this function, still nothing happens when devices get plugged in. > >> > IIUC this function disable the wakeup function, but what I want to do > >> > here is to have PME signal works even when runtime PM is enabled. > > > > This may indicate a bug in either the PCI or USB stacks (or both!). If > > a driver requires wakeup capability from runtime suspend but the device > > does not provide it, the PCI core should not allow the device to go > > into runtime suspend. Or is that the driver's responsibility? > > > >> > I also saw some legacy PCI PM stuff, so I also tried: > >> > device_set_wakeup_capable(&pdev->dev, 1); > >> > ...doesn't work either. > >> > > >> >> > >> >> Another alternative is to put the controller into D2 instead of D3, but > >> >> (1) I don't know how to do that, and (2) we don't know if wakeup > >> >> signalling works any better in D2 than it does in D3. > >> > > >> > I'll try if D2 works. > >> > >> Put the device into D2 instead of D3 can make the wakeup signaling > >> work, i.e. USB devices can be correctly detected after plugged into > >> EHCI port. > >> > >> Do you think this alternative an acceptable workaround? > > > > Yes, it is. The difficulty is that I don't know how to tell the PCI > > core that the device should go in D2 during runtime suspend instead of > > D3. Some sort of quirk may be needed -- perhaps Bjorn can help. > > > > FWIW, this is the diff I used to make the controller transits to D2 > instead of D3: > > diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c > index 563901cd9c06..36663688404a 100644 > --- a/drivers/pci/pci.c > +++ b/drivers/pci/pci.c > @@ -922,6 +922,9 @@ int pci_set_power_state(struct pci_dev *dev, > pci_power_t state) > if (dev->current_state == state) > return 0; > > + if (state > PCI_D2 && (dev->dev_flags & PCI_DEV_FLAGS_MAX_D2)) > + state = PCI_D2; > + > __pci_start_power_transition(dev, state); > > /* This device is quirked not to be put into D3, so > diff --git a/drivers/usb/host/ehci-pci.c b/drivers/usb/host/ehci-pci.c > index 93326974ff4b..a2c1fe62974a 100644 > --- a/drivers/usb/host/ehci-pci.c > +++ b/drivers/usb/host/ehci-pci.c > @@ -181,6 +181,8 @@ static int ehci_pci_setup(struct usb_hcd *hcd) > if (pdev->device == 0x7808) { > ehci->use_dummy_qh = 1; > ehci_info(ehci, "applying AMD > SB700/SB800/Hudson-2/3 EHCI dummy qh workaround\n"); > + > + pdev->dev_flags |= PCI_DEV_FLAGS_MAX_D2; > } > break; > case PCI_VENDOR_ID_VIA: > diff --git a/include/linux/pci.h b/include/linux/pci.h > index 8039f9f0ca05..6f86f2aa8548 100644 > --- a/include/linux/pci.h > +++ b/include/linux/pci.h > @@ -188,6 +188,7 @@ enum pci_dev_flags { > * the direct_complete optimization. > */ > PCI_DEV_FLAGS_NEEDS_RESUME = (__force pci_dev_flags_t) (1 << 11), > + PCI_DEV_FLAGS_MAX_D2 = (__force pci_dev_flags_t) (1 << 12), > }; > > enum pci_irq_reroute_variant { The lspci output [1] shows: 00:12.0 USB controller: Advanced Micro Devices, Inc. [AMD] FCH USB EHCI Controller (rev 39) (prog-if 20 [EHCI]) Capabilities: [c0] Power Management version 2 Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold+) Status: D3 NoSoftRst- PME-Enable+ DSel=0 DScale=0 PME- Bridge: PM- B3+ The device claims it can assert PME# from D3hot. If it can't, that sounds like a hardware defect that should be addressed with a quirk. Ideally we would also have a pointer to the AMD hardware erratum. Is the following path involved here? pci_finish_runtime_suspend target_state = pci_target_state() if (device_may_wakup()) if (dev->pme_support) ... pci_set_power_state(..., target_state) If so, I would naively expect that a quirk could clear the PCI_PM_CAP_PME_D3 and PCI_PM_CAP_PME_D3cold bits in dev->pme_support, and pci_target_state() would then avoid selecting D3 or D3cold. But I'm not an expert in power management. Bjorn [1] http://marc.info/?l=linux-usb&m=149570231732519&w=2
