Re: [PATCH] usb: xhci: prevent spurious root hub resume during suspend

[Mathias Nyman <mathias.nyman@linux.intel.com>]

On 6/30/26 11:43, Pei Xiao wrote:
> 
> 
> 在 2026/6/30 16:10, Mathias Nyman 写道:
>> On 6/30/26 10:36, Pei Xiao wrote:
>>> handle_port_status() unconditionally resumes the root hub when
>>> hcd->state is HC_STATE_SUSPENDED, regardless of whether a device is
>>> actually attached to the port.  This can cause system suspend to fail
>>> with -EBUSY if a spurious port change event arrives on an empty port
>>> after its bus has entered suspend.
>>>
>>> Fix this by checking PORT_CONNECT in handle_port_status() before
>>> resuming the root hub.  If no device is actually present on the port,
>>> the event is spurious and should be silently ignored rather than
>>> aborting suspend.
>>
>> Doesn't this change prevent handling device disconnects on suspended
>> hosts?
>>
> *Thank you for your reply. I’m not familiar with xHCI or these registers.
>   Can’t we tell the difference between a real unplug and a situation where
>   the device is physically still attached but portsc reports a disconnect?

Not really. In your case it really looks like a disconnect.

Port Status: 0x202a0
	Disconnected
	Disabled
	Link: Rx Detect
	Powered
	Unknown port speed
	Connect Status Change

Is it only this specific device that disconnects on suspend, or can this be
reproduced with any usb device?

Thanks
Mathias