Re: [PATCH] usb: xhci: prevent spurious root hub resume during suspend
From: Mathias Nyman
Date: Tue Jun 30 2026 - 06:35:16 EST
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:*Thank you for your reply. I’m not familiar with xHCI or these registers.
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?
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