On Thu, Jun 15, 2017 at 2:55 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Tue, 13 Jun 2017, Bjorn Helgaas wrote: > >> [+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. > >> 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. > > That's a good idea. However, we should apply the quirk only when it is > needed. Which means we need to know the numeric values for the PCI > IDs. Also, this will help searching for published errata. > > Kai-Heng, what does "lspci -nvs 00:12.0" show? 00:12.0 0c03: 1022:7808 (rev 39) (prog-if 20 [EHCI]) Subsystem: 1028:0732 Flags: bus master, 66MHz, medium devsel, latency 32, IRQ 18 Memory at fe769000 (32-bit, non-prefetchable) [size=256] Capabilities: [c0] Power Management version 2 Capabilities: [e4] Debug port: BAR=1 offset=00e0 Kernel driver in use: ehci-pci Here's the diff that can make it work: diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 1a14ca8965e6..7bd278535ab3 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -2208,6 +2208,12 @@ void pci_pm_init(struct pci_dev *dev) } pmc &= PCI_PM_CAP_PME_MASK; + + if (unlikely(dev->vendor == 0x1022 && dev->device == 0x7808)) { + dev_info(&dev->dev, "PME# does not work under D3, disabling it\n"); + pmc &= ~(PCI_PM_CAP_PME_D3 | PCI_PM_CAP_PME_D3cold); + } + if (pmc) { dev_printk(KERN_DEBUG, &dev->dev, "PME# supported from%s%s%s%s%s\n", If you think this is OK, I'll resend the patch. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
