ehci_hcd causes immediate wakeup from suspend to RAM or disk on Asus P4P800-VM

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Ondrej Zary

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Apr 27, 2010, 9:30:02 AM4/27/10
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Hello,
machine with Asus P4P800-VM mainboard wakes up immediately after:
echo mem >/sys/power/state
or even
echo disk >/sys/power/state (only when /sys/power/disk is set to "platform",
which is the default)

The problem disappears when unloading ehci_hcd module. There are no USB
devices attached. The problem seems to be something like this:
http://www.mail-archive.com/linux-usb-devel%40lists.sourceforge.net/msg54499.html

/sys/devices/pci0000:00/0000:00:1d.7/power/wakeup is disabled by default

/sys/devices/pci0000:00/0000:00:1d.7/usb1/power/wakeup is enabled by default,
changing it to disabled fixes the problem

The board has 4 USBPWxx jumpers (USBPW12, USBPW34, USBPW56 and USBPW78) that
selects 5V or 5VSB as power to the corresponding USB connectors. When they're
all set to 5VSB, the immediate wakeup does not appear. When any of them is
set to 5V, it wakes up immediately after entering suspend. I guess that the
loss of power to any of the ports (5V power is turned off in suspend) is
detected as some event (overcurrent or device connect?)

"ignore_oc=1" parameter to ehci_hcd modules does not change anything.

--
Ondrej Zary
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Ondrej Zary

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Apr 27, 2010, 10:30:02 AM4/27/10
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Disable wake on overcurrent in EHCI.
This fixes immediate resume from standby on boards where port power is lost
in standby which triggers overcurrent detection. At least Asus P4P800 boards
are affected when any of the USBPWxx (e.g. USBPW12) jumpers is set to 5V.
Tested on Asus P4P800-VM.

Signed-off-by: Ondrej Zary <li...@rainbow-software.org>

--- linux-source-2.6.33-orig/drivers/usb/host/ehci-hub.c 2010-02-24 19:52:17.000000000 +0100
+++ linux-source-2.6.33/drivers/usb/host/ehci-hub.c 2010-04-27 16:04:37.000000000 +0200
@@ -180,10 +180,10 @@ static int ehci_bus_suspend (struct usb_
* set), the port change detection will finally fix it.
*/
if (t1 & PORT_CONNECT) {
- t2 |= PORT_WKOC_E | PORT_WKDISC_E;
+ t2 |= PORT_WKDISC_E;
t2 &= ~PORT_WKCONN_E;
} else {
- t2 |= PORT_WKOC_E | PORT_WKCONN_E;
+ t2 |= PORT_WKCONN_E;
t2 &= ~PORT_WKDISC_E;
}
} else
@@ -912,7 +912,7 @@ static int ehci_hub_control (
* mode if we have hostpc feature
*/
temp &= ~PORT_WKCONN_E;
- temp |= PORT_WKDISC_E | PORT_WKOC_E;
+ temp |= PORT_WKDISC_E;
ehci_writel(ehci, temp | PORT_SUSPEND, status_reg);
if (hostpc_reg) {
spin_unlock_irqrestore(&ehci->lock, flags);

Ondrej Zary

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Apr 27, 2010, 12:30:03 PM4/27/10
to
The previous patch was not enough as it worked only when there were no USB
devices connected. With a bus-powered device connected, power loss causes
disconnect which wakes up the machine immediately again.

Does anyone know why is this enabled by default? No other USB host driver
(except oxu210hp-hcd which is based on EHCI) does that. This also means that
suspended laptop wakes up when disconnecting a mouse? I don't have any to test
right now. Wakeup on USB connect makes a bit more sense but I'd say that it's
still not a good idea to enable it by default.

If we don't need that, perhaps the following patch should be applied.


Disable wake on overcurrent and disconnect in EHCI.


This fixes immediate resume from standby on boards where port power is lost

in standby which triggers overcurrent detection and disconnect if a
bus-powered device is connected. At least Asus P4P800 boards are affected when


any of the USBPWxx (e.g. USBPW12) jumpers is set to 5V.
Tested on Asus P4P800-VM.

Signed-off-by: Ondrej Zary <li...@rainbow-software.org>

--- linux-source-2.6.33-orig/drivers/usb/host/ehci-hub.c 2010-02-24 19:52:17.000000000 +0100

+++ linux-source-2.6.33/drivers/usb/host/ehci-hub.c 2010-04-27 18:17:36.000000000 +0200
@@ -173,21 +173,16 @@ static int ehci_bus_suspend (struct usb_
}

/* enable remote wakeup on all ports */
+ t2 &= ~PORT_WAKE_BITS;
if (hcd->self.root_hub->do_remote_wakeup) {
/* only enable appropriate wake bits, otherwise the
* hardware can not go phy low power mode. If a race
* condition happens here(connection change during bits


* set), the port change detection will finally fix it.
*/

- if (t1 & PORT_CONNECT) {


- t2 |= PORT_WKOC_E | PORT_WKDISC_E;

- t2 &= ~PORT_WKCONN_E;
- } else {


- t2 |= PORT_WKOC_E | PORT_WKCONN_E;

- t2 &= ~PORT_WKDISC_E;
- }
- } else
- t2 &= ~PORT_WAKE_BITS;
+ if (!(t1 & PORT_CONNECT))
+ t2 |= PORT_WKCONN_E;
+ }

if (t1 != t2) {
ehci_vdbg (ehci, "port %d, %08x -> %08x\n",

Alan Stern

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Apr 27, 2010, 3:30:02 PM4/27/10
to
On Tue, 27 Apr 2010, Ondrej Zary wrote:

> The previous patch was not enough as it worked only when there were no USB
> devices connected. With a bus-powered device connected, power loss causes
> disconnect which wakes up the machine immediately again.

You said earlier that the host controller was disabled for remote
wakeup ("/sys/devices/pci0000:00/0000:00:1d.7/power/wakeup is disabled
by default"). So even though the root hub might issue a wakeup
request, the controller hardware should not forward that request to the
PCI bus and it should not cause the system to wake up.

> Does anyone know why is this enabled by default?

Why _what_ is enabled? Detection of disconnects? Because otherwise
your computer wouldn't realize anything had happened when a suspended
USB device was unplugged from a suspended root hub.

> No other USB host driver
> (except oxu210hp-hcd which is based on EHCI) does that.

Look again -- they all do. (All the HCDs that support suspend/resume,
anyway.)

> This also means that
> suspended laptop wakes up when disconnecting a mouse?

No, for the reason I described above. The controller is aware of the
wakeup request but doesn't generate a PME# event. Likewise for desktop
systems.

> I don't have any to test
> right now. Wakeup on USB connect makes a bit more sense but I'd say that it's
> still not a good idea to enable it by default.
>
> If we don't need that, perhaps the following patch should be applied.
>
>
> Disable wake on overcurrent and disconnect in EHCI.
> This fixes immediate resume from standby on boards where port power is lost
> in standby which triggers overcurrent detection and disconnect if a
> bus-powered device is connected. At least Asus P4P800 boards are affected when
> any of the USBPWxx (e.g. USBPW12) jumpers is set to 5V.

Why would you want to change the jumper settings? Host controllers are
_supposed_ to supply 5V power during system suspend.

Alan Stern

Ondrej Zary

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Apr 27, 2010, 4:50:01 PM4/27/10
to
On Tuesday 27 April 2010 21:21:23 Alan Stern wrote:
> On Tue, 27 Apr 2010, Ondrej Zary wrote:
> > The previous patch was not enough as it worked only when there were no
> > USB devices connected. With a bus-powered device connected, power loss
> > causes disconnect which wakes up the machine immediately again.
>
> You said earlier that the host controller was disabled for remote
> wakeup ("/sys/devices/pci0000:00/0000:00:1d.7/power/wakeup is disabled
> by default"). So even though the root hub might issue a wakeup
> request, the controller hardware should not forward that request to the
> PCI bus and it should not cause the system to wake up.

Maybe it should not - but it wakes up this board and probably also P4P800,
P4P800-E and P4C800-E at least:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/75497

> > Does anyone know why is this enabled by default?
>
> Why _what_ is enabled? Detection of disconnects? Because otherwise
> your computer wouldn't realize anything had happened when a suspended
> USB device was unplugged from a suspended root hub.

That's not disconnect detection - that's wakeup on disconnect. If I understand
EHCI 1.0 specification correctly, disconnect detection should work regardless
of the state of this bit:
| PORTSC bit 21: Wake on Disconnect Enable (WKDSCNNT_E):
| R/W. Default = 0b.
| Writing this bit to a one enables the port to be sensitive to device
| disconnects as wake-up events. See Section 4.3 for effects of this bit on
| resume event behavior. Refer to Section 4.3.1 for operational model.

And it really does. With this patch applied, system does not wake up when a
device is disconnected during suspend. When I wake up the system manually,
the disconnect is detected immediately (does not matter

> > No other USB host driver
> > (except oxu210hp-hcd which is based on EHCI) does that.
>
> Look again -- they all do. (All the HCDs that support suspend/resume,
> anyway.)
>
> > This also means that
> > suspended laptop wakes up when disconnecting a mouse?
>
> No, for the reason I described above. The controller is aware of the
> wakeup request but doesn't generate a PME# event. Likewise for desktop
> systems.
>
> > I don't have any to test
> > right now. Wakeup on USB connect makes a bit more sense but I'd say that
> > it's still not a good idea to enable it by default.
> >
> > If we don't need that, perhaps the following patch should be applied.
> >
> >
> > Disable wake on overcurrent and disconnect in EHCI.
> > This fixes immediate resume from standby on boards where port power is
> > lost in standby which triggers overcurrent detection and disconnect if a
> > bus-powered device is connected. At least Asus P4P800 boards are affected
> > when any of the USBPWxx (e.g. USBPW12) jumpers is set to 5V.
>
> Why would you want to change the jumper settings? Host controllers are
> _supposed_ to supply 5V power during system suspend.

Maybe because I don't want all my USB devices to be powered when the system is
turned off. I doubt that laptop in suspend-to-RAM (on battery) provides power
to USB ports.

--
Ondrej Zary

Greg KH

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Apr 27, 2010, 5:40:02 PM4/27/10
to
On Tue, Apr 27, 2010 at 10:46:48PM +0200, Ondrej Zary wrote:
> > Why would you want to change the jumper settings? Host controllers are
> > _supposed_ to supply 5V power during system suspend.
>
> Maybe because I don't want all my USB devices to be powered when the system is
> turned off. I doubt that laptop in suspend-to-RAM (on battery) provides power
> to USB ports.

On the contrary, it does. Some of us use this mode to charge devices :)

thanks,

greg k-h

Alan Stern

unread,
Apr 28, 2010, 11:50:03 AM4/28/10
to
On Tue, 27 Apr 2010, Ondrej Zary wrote:

> On Tuesday 27 April 2010 21:21:23 Alan Stern wrote:
> > On Tue, 27 Apr 2010, Ondrej Zary wrote:
> > > The previous patch was not enough as it worked only when there were no
> > > USB devices connected. With a bus-powered device connected, power loss
> > > causes disconnect which wakes up the machine immediately again.
> >
> > You said earlier that the host controller was disabled for remote
> > wakeup ("/sys/devices/pci0000:00/0000:00:1d.7/power/wakeup is disabled
> > by default"). So even though the root hub might issue a wakeup
> > request, the controller hardware should not forward that request to the
> > PCI bus and it should not cause the system to wake up.
>
> Maybe it should not - but it wakes up this board and probably also P4P800,
> P4P800-E and P4C800-E at least:
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/75497

Okay, evidently the hardware or firmware on these boards is buggy.
Other systems do not have the same problem, as far as I know.

> > > Does anyone know why is this enabled by default?
> >
> > Why _what_ is enabled? Detection of disconnects? Because otherwise
> > your computer wouldn't realize anything had happened when a suspended
> > USB device was unplugged from a suspended root hub.
>
> That's not disconnect detection - that's wakeup on disconnect.

True; I oversimplified. Furthermore, starting in 2.6.34, the wakeup
settings during system sleep (suspend or hibernation) can be different
from the settings during autosuspend, so you can have root hubs enabled
for wakeup during autosuspend but not during system sleep.

> If I understand
> EHCI 1.0 specification correctly, disconnect detection should work regardless
> of the state of this bit:
> | PORTSC bit 21: Wake on Disconnect Enable (WKDSCNNT_E):
> | R/W. Default = 0b.
> | Writing this bit to a one enables the port to be sensitive to device
> | disconnects as wake-up events. See Section 4.3 for effects of this bit on
> | resume event behavior. Refer to Section 4.3.1 for operational model.
>
> And it really does. With this patch applied, system does not wake up when a
> device is disconnected during suspend. When I wake up the system manually,
> the disconnect is detected immediately (does not matter

It's worth pointing out that EHCI is different in this respect from
OHCI and UHCI; the older controllers do not have the capability to
enable or disable wakeup independently for connect, disconnect, and
overcurrent events. They are all or nothing. So are external USB
hubs.


> > > If we don't need that, perhaps the following patch should be applied.
> > >
> > >
> > > Disable wake on overcurrent and disconnect in EHCI.
> > > This fixes immediate resume from standby on boards where port power is
> > > lost in standby which triggers overcurrent detection and disconnect if a
> > > bus-powered device is connected. At least Asus P4P800 boards are affected
> > > when any of the USBPWxx (e.g. USBPW12) jumpers is set to 5V.
> >
> > Why would you want to change the jumper settings? Host controllers are
> > _supposed_ to supply 5V power during system suspend.
>
> Maybe because I don't want all my USB devices to be powered when the system is
> turned off. I doubt that laptop in suspend-to-RAM (on battery) provides power
> to USB ports.

This depends on how your system was turned off. During suspend or
hibernation, you _should_ want USB devices to be powered (and some
people do, as Greg pointed out). During a normal system shutdown, the
USB buses should not be powered.

Regardless, I don't think a kernel patch is the way to solve your
problem. Changing the wakeup setting for the root hub will do what you
want, and that setting is explicitly intended to be controlled by
userspace (after all, that's why it is exposed in sysfs). The initial
value is only a reasonable default; you can certainly add scripts or
udev rules to disable wakeup on your EHCI root hub.

Alan Stern

Ondrej Zary

unread,
Apr 28, 2010, 1:40:01 PM4/28/10
to
On Wednesday 28 April 2010 17:41:30 Alan Stern wrote:
> On Tue, 27 Apr 2010, Ondrej Zary wrote:
> > On Tuesday 27 April 2010 21:21:23 Alan Stern wrote:
> > > On Tue, 27 Apr 2010, Ondrej Zary wrote:
> > > > The previous patch was not enough as it worked only when there were
> > > > no USB devices connected. With a bus-powered device connected, power
> > > > loss causes disconnect which wakes up the machine immediately again.
> > >
> > > You said earlier that the host controller was disabled for remote
> > > wakeup ("/sys/devices/pci0000:00/0000:00:1d.7/power/wakeup is disabled
> > > by default"). So even though the root hub might issue a wakeup
> > > request, the controller hardware should not forward that request to the
> > > PCI bus and it should not cause the system to wake up.
> >
> > Maybe it should not - but it wakes up this board and probably also
> > P4P800, P4P800-E and P4C800-E at least:
> > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/75497
>
> Okay, evidently the hardware or firmware on these boards is buggy.
> Other systems do not have the same problem, as far as I know.

It works fine in Windows.

Now I took another machine - IBM ThinkCentre M51 (i915+ICH6). USB ports are
powered in suspend here so it does not resume immediately. But
connecting/disconnecting an USB device wakes it up from suspend. Only in
Linux, not in Windows.

Yes, I can work around that. But many users can't. This is an attempt to make
it "just work".

I'm trying to say that the "wakeup on everything" is not a good thing (if not
a bug). Who needs it? I can't imagine any real use for it. It clearly breaks
suspend on some systems and is annoying on other. Who expects that
disconnecting a device should wake up sleeping machine?

When all these three wakeups (overcurrent, connect, disconnect) are disabled,
we lose nothing. Connect/disconnect detection works fine after wakeup. Wakeup
by USB devices (not by connect/disconnect but by the device itself signaling
a resume) is completely independent of this (according to EHCI
specification).


--
Ondrej Zary

Alan Stern

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Apr 30, 2010, 4:20:01 PM4/30/10
to
On Wed, 28 Apr 2010, Ondrej Zary wrote:

> On Wednesday 28 April 2010 17:41:30 Alan Stern wrote:
> > On Tue, 27 Apr 2010, Ondrej Zary wrote:
> > > On Tuesday 27 April 2010 21:21:23 Alan Stern wrote:
> > > > On Tue, 27 Apr 2010, Ondrej Zary wrote:
> > > > > The previous patch was not enough as it worked only when there were
> > > > > no USB devices connected. With a bus-powered device connected, power
> > > > > loss causes disconnect which wakes up the machine immediately again.
> > > >
> > > > You said earlier that the host controller was disabled for remote
> > > > wakeup ("/sys/devices/pci0000:00/0000:00:1d.7/power/wakeup is disabled
> > > > by default"). So even though the root hub might issue a wakeup
> > > > request, the controller hardware should not forward that request to the
> > > > PCI bus and it should not cause the system to wake up.
> > >
> > > Maybe it should not - but it wakes up this board and probably also
> > > P4P800, P4P800-E and P4C800-E at least:
> > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/75497
> >
> > Okay, evidently the hardware or firmware on these boards is buggy.
> > Other systems do not have the same problem, as far as I know.

I take this back. The same thing happens on my machine (Intel ICH5
chipset). I'd guess there is a bug in the PCI or ACPI subsystem, but
more testing is needed before I can be sure. Somehow the PCI or
platform wakeup mechanism gets activated even when it is supposed to be
disabled.

> It works fine in Windows.

How can you tell? How do you know what values Windows writes into the
EHCI port control registers?

> > Regardless, I don't think a kernel patch is the way to solve your
> > problem. Changing the wakeup setting for the root hub will do what you
> > want, and that setting is explicitly intended to be controlled by
> > userspace (after all, that's why it is exposed in sysfs). The initial
> > value is only a reasonable default; you can certainly add scripts or
> > udev rules to disable wakeup on your EHCI root hub.
>
> Yes, I can work around that. But many users can't. This is an attempt to make
> it "just work".

It should "just work" already. The fact that it doesn't means there is
a bug. At the moment I can't be sure where the bug is -- but even if
it is in ehci-hcd, your suggested patch isn't the right fix.

> I'm trying to say that the "wakeup on everything" is not a good thing (if not
> a bug). Who needs it?

I don't know, and neither do you. But the USB spec requires this
behavior from external hubs, so evidently _somebody_ thought it was a
good idea.

> I can't imagine any real use for it. It clearly breaks
> suspend on some systems and is annoying on other.

If everything was working properly, the machine wouldn't wake up when a
disconnect occurred.

> Who expects that
> disconnecting a device should wake up sleeping machine?

Perhaps the same people who expect that plugging in a device should
wake up a sleeping machine?

> When all these three wakeups (overcurrent, connect, disconnect) are disabled,
> we lose nothing. Connect/disconnect detection works fine after wakeup. Wakeup
> by USB devices (not by connect/disconnect but by the device itself signaling
> a resume) is completely independent of this (according to EHCI
> specification).

What about UHCI or OHCI? What about external hubs?

In short, why should EHCI behave differently from everything else?

Alan Stern

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