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

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Message-ID: <517B18E2.3060408@hp.com>
Date:	Sat, 27 Apr 2013 08:16:34 +0800
From:	ZhenHua <zhen-hual@...com>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	gregkh@...uxfoundation.org, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] driver,usb: Fix a warning in uhci-hcd driver

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.

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.

Thanks
Zhen-Hua
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