linux-kernel - Re: Question about failure in PCI power-state change

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Date:	Sat, 08 Sep 2012 17:01:28 -0500
From:	Larry Finger <Larry.Finger@...inger.net>
To:	Alan Stern <stern@...land.harvard.edu>
CC:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
	LKML <linux-kernel@...r.kernel.org>,
	李朝明 <chaoming_li@...lsil.com.cn>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Huang Ying <ying.huang@...el.com>
Subject: Re: Question about failure in PCI power-state change

On 09/08/2012 04:50 PM, Alan Stern wrote:
> On Sat, 8 Sep 2012, Rafael J. Wysocki wrote:
>
>> On Saturday, September 08, 2012, Bjorn Helgaas wrote:
>>> +cc Rafael, Huang, linux-pm
>>>
>>> On Fri, Sep 7, 2012 at 3:44 PM, Larry Finger <Larry.Finger@...inger.net> wrote:
>>>> Hi,
>>>>
>>>> On occasion when I unload and reload driver rtl8192ce, I get the message
>>>>
>>>> "Refused to change power state, currently in D3"
>>>>
>>>> I added additional info to the printk and discovered that it was trying to
>>>> change to state D0. The problem seems to occur when I have made a
>>>> connection, unloaded the driver, and reloaded it. If I do not make a
>>>> connection before unloading, then the problem is a lot less likely.
>>>>
>>>> This is with kernel 3.6-rc4 from wireless-testing. A Google search shows
>>>> that the problem is usually due to suspend/resume difficulties, but this
>>>> machine has not been suspended.
>>>>
>>>> I would appreciate any help that you might give in solving this issue.
>>
>> I think writing "on" to the /sys/devices/.../power/control attribute of the device
>> in question would help.
>
> Are you suggesting that this particular wireless adapter is unable to
> return to D0 from D3?
>
> Larry, what happens if you try the suspend & resume your system while
> there's a connection?  Does a similar error occur during the resume?

After I sent this request, I found an error in the removal process for this 
particular adapter, which I suspect is the real source of the problem. That 
difficulty is only found on the new variant of the card - the older one is OK. I 
think the problem is that the adapter is left in some ill-defined state that can 
only be cleared by doing a power reset. In that state, it is unable to return to D0.

This box has never been able to suspend/resume, thus I cannot answer the other 
question.

Thanks to all that responded. Once I clean up the other error, I will recontact 
the list if the D3 => D0 problem persists.

Larry


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