linux-kernel - Re: [PATCH] usb:solve resume usb device identification problem

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Date:	Tue, 12 Jul 2016 10:23:52 +0800
From:	Lu Baolu <baolu.lu@...ux.intel.com>
To:	Lipengcheng <lpc.li@...ilicon.com>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"stern@...land.harvard.edu" <stern@...land.harvard.edu>,
	"chasemetzger15@...il.com" <chasemetzger15@...il.com>,
	"mathias.nyman@...ux.intel.com" <mathias.nyman@...ux.intel.com>,
	"oneukum@...e.com" <oneukum@...e.com>,
	"jun.li@...escale.com" <jun.li@...escale.com>
Cc:	"linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] usb:solve resume usb device identification problem

Hi,

On 07/12/2016 09:48 AM, Lipengcheng wrote:
> Hi,
>
>> -----Original Message-----
>> From: Lu Baolu [mailto:baolu.lu@...ux.intel.com]
>> Sent: Tuesday, July 12, 2016 8:42 AM
>> To: Lipengcheng; gregkh@...uxfoundation.org; stern@...land.harvard.edu; chasemetzger15@...il.com; mathias.nyman@...ux.intel.com;
>> oneukum@...e.com; jun.li@...escale.com
>> Cc: linux-usb@...r.kernel.org; linux-kernel@...r.kernel.org
>> Subject: Re: [PATCH] usb:solve resume usb device identification problem
>>
>> Hi,
>>
>> On 07/11/2016 08:57 PM, Pengcheng Li wrote:
>>> A usb device in the connection state. Then host is suspend and resume.
>>> But the usb device could not be at the right speed. We should be reset
>>> the reset.
>> Have you tried applying XHCI_RESET_ON_RESUME quirk to your host controller driver? Is your usb device self powered?
>>
> I do not apply XHCI_RESET_ON_RESUME quir to my host controller driver. I select no pci platform. Our usb device is not self powered.

This quirk is not pci specific.

>> Best regards,
>> Lu  Baolu
>>
>>> Signed-off-by: Pengcheng Li <lpc.li@...ilicon.com>
>>> ---
>>>  drivers/usb/core/hub.c | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index
>>> bee1351..cd71bb3 100644
>>> --- a/drivers/usb/core/hub.c
>>> +++ b/drivers/usb/core/hub.c
>>> @@ -3455,7 +3455,7 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
>>>  	struct usb_hub	*hub = usb_hub_to_struct_hub(udev->parent);
>>>  	struct usb_port *port_dev = hub->ports[udev->portnum  - 1];
>>>  	int		port1 = udev->portnum;
>>> -	int		status;
>>> +	int		status, retval;
>>>  	u16		portchange, portstatus;
>>>
>>>  	if (!test_and_set_bit(port1, hub->child_usage_bits)) { @@ -3512,6
>>> +3512,10 @@ int usb_port_resume(struct usb_device *udev, pm_message_t msg)
>>>  		}
>>>  	}
>>>
>>> +	retval = hub_port_reset(hub, port1, udev, HUB_ROOT_RESET_TIME, false);
>>> +	if (retval < 0)
>>> +		hub_port_disable(hub, port1, 0);
>>> +

If I understand it right, this is a "host + device" specific issue. This line of code
might solve your issue, but it impacts all other hosts and devices which don't
have such problem.

Best regards,
Lu Baolu