Re: PCI PME# routing problem?

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On Tue, 27 Sep 2011, Rafael J. Wysocki wrote:

> > > What's there in /proc/acpi/wakeup ?
> > 
> > Here it is:
> > 
> > Device	S-state	  Status   Sysfs node
> > P0P4	  S4	*disabled  pci:0000:00:1e.0
> > MC97	  S4	*disabled  
> > USB1	  S4	*enabled   pci:0000:00:1d.0
> > USB2	  S4	*enabled   pci:0000:00:1d.1
> > USB3	  S4	*enabled   pci:0000:00:1d.2
> > USB4	  S4	*enabled   pci:0000:00:1d.3
> > EUSB	  S4	*enabled   pci:0000:00:1d.7
> > PS2K	  S4	*enabled   pnp:00:09
> > PS2M	  S4	*disabled  pnp:00:0a
> > GBEN	  S4	*disabled  
> > 
> > Of course the 000:01:01.1 device isn't on the list, because it's part
> > of an add-on PCI card, not built into the motherboard.
> > 
> > I tried echoing "P0P4" to /proc/acpi/wakeup, which caused the first 
> > line above to say "enabled", but there was no difference in behavior.  
> > Is the fact that the S-state column says S4 relevant (bearing in mind 
> > that the test does an S3 suspend)?
> > 
> > I also checked the setting of 
> > /sys/bus/pci/devices/0000:00:1e.0/power/wakeup, and it says "enabled"
> > following the write to /proc/acpi/wakeup.
> 
> That's how it is supposed to work.
> 
> > Now, it's possible that the problem is at a lower level.  Maybe the 
> > device is not getting wakeup power even though it's supposed to be in 
> > D3hot.
> 
> That's possible.  Moreover, it is possible that the BIOS removes power
> from the bus segment the device is on entirely, in which case it would
> need the auxiliary power source to generate wakeup events.

Is there any way to find out whether this is happening?

> > I don't know how to check that, however, or how to see whether 
> > or not its PME# signal is asserted when the system wakes up.  By the 
> > time the system finishes resuming it is too late, because the driver's 
> > resume routine does a complete reset of the device (not to mention that 
> > the PCI subsystem's resume routine restores the device's config space 
> > contents and disables PME#).
> 
> Hmm.  Does the device report being able to generate wakeup events from D3_cold?

# lspci -vv -s 1:01.01
01:01.1 USB Controller: NEC Corporation USB (rev 43) (prog-if 10 [OHCI])
	Subsystem: NEC Corporation Hama USB 2.0 CardBus
	Control: I/O- Mem+ BusMaster+ SpecCycle- MemWINV+ VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx-
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=medium >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 32 (250ns min, 10500ns max), Cache Line Size: 32 bytes
	Interrupt: pin B routed to IRQ 23
	Region 0: Memory at fe5de000 (32-bit, non-prefetchable) [size=4K]
	Capabilities: [40] Power Management version 2
		Flags: PMEClk- DSI- D1+ D2+ AuxCurrent=0mA PME(D0+,D1+,D2+,D3hot+,D3cold-)
		Status: D0 NoSoftRst- PME-Enable- DSel=0 DScale=0 PME-
	Kernel driver in use: ohci_hcd
	Kernel modules: ohci-hcd

Apparently not.

Alan Stern


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