Re: [PATCH 1/1] driver,usb: Fix a warning in uhci-hcd driver

From: ZhenHua
Date: Sat Apr 27 2013 - 21:52:08 EST

On 04/27/2013 11:14 PM, Alan Stern wrote:
On Sat, 27 Apr 2013, ZhenHua wrote:

On 04/27/2013 12:51 AM, Alan Stern wrote:
On Fri, 26 Apr 2013, ZhenHua wrote:

There is a function wait_for_HP() in uhci-hub.c. In this
patch, it is used in suspend_rh(), I think this can be a
solution. And I have tested this patch, it can fix the bug.

I think there is another patch needed. As Alan said in another
mail, in the UHCI_RH_RUNNING_NODEVS case, it should not be stopped
if the uhci device is HP iLo virtual usb.
I believe that if you change the UHCI_RH_RUNNING_NODEVS case, you will
find that this patch (calling wait_for_HP) isn't needed.

In fact, the patch is so easy that I am including it below. Please
test this (without either of your patches) to see if it works.

Alan Stern

Index: usb-3.9/drivers/usb/host/uhci-hub.c
--- usb-3.9.orig/drivers/usb/host/uhci-hub.c
+++ usb-3.9/drivers/usb/host/uhci-hub.c
@@ -225,7 +225,8 @@ static int uhci_hub_status_data(struct u
/* auto-stop if nothing connected for 1 second */
if (any_ports_active(uhci))
uhci->rh_state = UHCI_RH_RUNNING;
- else if (time_after_eq(jiffies, uhci->auto_stop_time))
+ else if (time_after_eq(jiffies, uhci->auto_stop_time) &&
+ !uhci->wait_for_hp)
suspend_rh(uhci, UHCI_RH_AUTO_STOPPED);

I have tested the UHCI_RH_RUNNING_NODEVS case yeasterday, and it works.
But the function suspend_rh is also called in other places, so I think
it only fixes
the warning when auto stop is called, but not fix the warning when
uhci's bus_suspend
is called, it will come out again.
Have you tried this? I expect the warning will not occur when the
bus_suspend routine is called, because then there will be a 1-ms delay,
not just a 400-us delay.
I tested this, and the warning is gone. Is this patch committed ?
I need to paste the link to suse bugzilla.

And if you add uhci->wait_for_hp check in the UHCI_RH_RUNNING_NODEVS case,
all hp uhci devices will not auto stop, not only the virtual devices. I
guess it may waste resource.
If you want, you can add a new flag specifically for virtual
controllers. But it shouldn't matter -- as long as your kernels are
built with CONFIG_PM_RUNTIME enabled, there won't be any significant
waste of resources.

Alan Stern

I think we can check the product id to determine whether a device is virtual.
Do you know if there is another way to check this?

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