New: Regression: Upgrading from 5.9.8 to 5.9.9 stops ME906s LTE mobile modem from working.

https://bugzilla.kernel.org/show_bug.cgi?id=210565

            Bug ID: 210565
           Summary: Regression: Upgrading from 5.9.8 to 5.9.9 stops ME906s
                    LTE mobile modem from working.
           Product: Drivers
           Version: 2.5
    Kernel Version: 5.9.9
          Hardware: Intel
                OS: Linux
              Tree: Mainline
            Status: NEW
          Severity: high
          Priority: P1
         Component: USB
          Assignee: [email protected]
          Reporter: [email protected]
        Regression: No

The device: 12d1:15c1 Huawei Technologies Co., Ltd. ME906s LTE M.2 Module has been working perfectly, up until kernel release 5.9.9.

On 5.9.9, I get errors like:

Dec 09 08:40:25 x1 NetworkManager[531]: <info>  [1607456425.9474] device
(cdc-wdm0): Activation: successful, device activated.
Dec 09 08:40:41 x1 ModemManager[570]: [/dev/cdc-wdm0] unexpected port hangup!
Dec 09 08:40:41 x1 ModemManager[570]: [/dev/cdc-wdm0] channel destroyed
Dec 09 08:40:41 x1 ModemManager[570]: <info>  [modem2] connection to mbim-proxy
for /dev/cdc-wdm0 lost, reprobing
Dec 09 08:40:41 x1 NetworkManager[531]: <info>  [1607456441.0644] device
(cdc-wdm0): state change: activated -> unmanaged (reason 'removed',
sys-iface-state: 'removed')
Dec 09 08:41:06 x1 kernel: cdc_ether 1-2:2.0 wwan0: register 'cdc_ether' at
usb-0000:00:14.0-2, Mobile Broadband Network Device, 02:1e:10:1f:00:00
Dec 09 08:41:06 x1 kernel: usbcore: registered new interface driver cdc_ether
Dec 09 08:41:06 x1 kernel: cdc_ether 1-2:2.0 wwp0s20f0u2c2: renamed from wwan0
Dec 09 08:41:07 x1 kernel: cdc_ether 1-2:2.0 wwp0s20f0u2c2: unregister

'cdc_ether' usb-0000:00:14.0-2, Mobile Broadband Network Device

It works fine if I downgrade to 5.9.8.

I have also tested 5.9.10, 5.9.11 and 5.9.12, all of which this device no longer works.

I can see commit ebc047afe9d2f04fdfd81d74e6c32bb3671b4670 in the change log that touches the cdc driver, so wonder if this is related.

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https://bugzilla.kernel.org/show_bug.cgi?id=210565

--- Comment #1 from Glen Ogilvie ([email protected]) --- On further digging, it's seems that 5.9.8 is also not working after a full power off/power on.

Moving down to 5.9.3 seems to have got it to work again.

Maybe commit: 88a559432e1f3f909941f0a3ec857465db24a784

If I can find time, I might take a current kernel and undoing these commits and see if it fixes it, unless someone has a better idea.

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Glen Ogilvie ([email protected]) changed:

What |Removed |Added
----------------------------------------------------------------------------

             Status|NEW                         |RESOLVED
         Resolution|---                         |INVALID

--- Comment #2 from Glen Ogilvie ([email protected]) --- Appears to work in 5.9.13.

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