RE: [PATCH] usb:solve resume usb device identification problem

[Lipengcheng]

> -----Original Message-----
> From: Lu Baolu [mailto:baolu.lu@xxxxxxxxxxxxxxx]
> Sent: Tuesday, July 12, 2016 10:24 AM
> To: Lipengcheng; gregkh@xxxxxxxxxxxxxxxxxxx; stern@xxxxxxxxxxxxxxxxxxx; chasemetzger15@xxxxxxxxx; mathias.nyman@xxxxxxxxxxxxxxx;
> oneukum@xxxxxxxx; jun.li@xxxxxxxxxxxxx
> Cc: linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> 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@xxxxxxxxxxxxxxx]
> >> Sent: Tuesday, July 12, 2016 8:42 AM
> >> To: Lipengcheng; gregkh@xxxxxxxxxxxxxxxxxxx;
> >> stern@xxxxxxxxxxxxxxxxxxx; chasemetzger15@xxxxxxxxx;
> >> mathias.nyman@xxxxxxxxxxxxxxx; oneukum@xxxxxxxx; jun.li@xxxxxxxxxxxxx
> >> Cc: linux-usb@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
> >> 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.
> 
I'm sorry. I will try to it.
> >> Best regards,
> >> Lu  Baolu
> >>
> >>> Signed-off-by: Pengcheng Li <lpc.li@xxxxxxxxxxxxx>
> >>> ---
> >>>  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.
> 
Yes. You are right. This line of code can solve my issue. But I suspect this is a common issue. At normal enumeration, the device has a reset operation. The resume
should have the same operation. In USB3.0 spec, superspeed device is at the wrong statue(u2 statue), and we should be reset the device.
> Best regards,
> Lu Baolu

Best regards,
Pengcheng Li