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

[ZhenHua]

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);
> > >    		break;
> > >    
> > 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?

Thanks
Zhen-Hua
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