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From: Mathias Nyman <mathias.nyman@linux.intel.com>
To: Mark Hills <mark@xwax.org>
Cc: linux-usb@vger.kernel.org
Subject: Re: XHCI unplug of USB-C device is not detected
Date: Mon, 15 Nov 2021 23:00:10 +0200	[thread overview]
Message-ID: <597a8c22-3a0a-23c4-396b-fb539916a4c2@linux.intel.com> (raw)
In-Reply-To: <2111061157310.2377@stax.localdomain>

On 6.11.2021 14.23, Mark Hills wrote:
> 
>> Also see if disabling runtime suspend for both roothubs helps:
>> # echo on > /sys/bus/usb/devices/usb1/power/control
>> # echo on > /sys/bus/usb/devices/usb2/power/control
> 
> Yes, it helps. I pinpointed it on usb3. The webcam can now be plugged and 
> re-plugged. It also survives a suspend/resume of the machine now and I can 
> see the change in portsc:
> 
>   -Powered Connected Enabled Link:U3 PortSpeed:4 Change: Wake:
>   +Powered Not-connected Disabled Link:RxDetect PortSpeed:0 Change: Wake:
> 
> So it seems this is a workaround -- thank you.
> 
> Is it worth getting to the root of this problem (and can I capture any 
> data to help?) or is it just that some devices are buggy?

To me this looks more like a like a wakeup issue on your platform than a buggy usb device.
I'd look more into the what PCI D state the xHC controller is put into during
runtime suspend, and make sure it actually can generate a PME wake from that state. 
PCI code will select D state based on values from ACPI firmware DSDT tables so those might
be worth looking into. 

Assuming of course this is a PCI xhci controller  

-Mathias 



      reply	other threads:[~2021-11-15 21:32 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-05 10:58 XHCI unplug of USB-C device is not detected Mark Hills
2021-11-05 20:40 ` Mathias Nyman
2021-11-06 12:23   ` Mark Hills
2021-11-15 21:00     ` Mathias Nyman [this message]

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