Thanks Mathias for looking into this.

2018-02-06 18:32 GMT+01:00 Mathias Nyman <>:
> Does reverting
> 37be6676 usb: hub: Fix auto-remount of safely removed or ejected USB-3
> devices
> help?

Unfortunately not, the card reader is still missing after resume.

Here's the dmesg and usbmon (as previously, doing one suspend-resume cycle):

For this log I also increased the usbmon buffer size as suggested by
Alan (to about 2MB). This (seemingly) resolved the issue with the log

The reset resume of device "usb 2-4" (the device in question) happens
around [100.77].
In the usbmon log there is no activity at that exact time, only ~50ms
before and after. Can we infer from this that the issue is independent
from the actual device and must stem from some faulty state in the
kernel or USB controller?

Btw I also added/modified some debug lines for my own understanding,
those are tagged with "[CUSTOM LOG]".

> * check that root cause for failing USB3 device reset after resume is not
> that several
>   xhci slots are in Default state at the same time. xHC can't handle this.
>   In normal device enumeration usb core has a mutex protecting it, not sure
> it works here,
>   maybe usb core and xhci are out of sync after xHC reset?

I find this line in particular interesting:
[ 100.771536] xhci_hcd 0000:00:14.0: [CUSTOM LOG] xHCI
xhci_urb_enqueue called with unaddressed device, slot_id = 1
This comes from xhci_check_args(). Since udev->slot_id == 1 is
non-zero this implies that xhci->devs[udev->slot_id] must be NULL for
this particular device (usb 2-4), which I guess is not good. So to me
this does indeed look like the usb core and xhci are out of sync.

However I'm not familiar with the code (for instance what is slot_id
is for, who uses it, should it always be 0 on resume?) but based on
the log and what you wrote I guess this sounds like a good point:

> * make sure xhci sets udev->slot_id to zero when xhci slots are disabled.
>   Slots are disabled and freed when xHC is reset at resume in this case.
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