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Groups > linux.debian.kernel > #92247

Bug#1127678: linux-image-6.12.69+deb13-amd64: Kernel module rtw_usb fails to detect usb wifi dongle with RTL8811AU chipset

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Hello Uwe,

Am 18.02.26 um 17:19 schrieb Uwe Kleine-König:
> Control: tag -1 + moreinfo
>
> Hello,
>
> On Wed, Feb 11, 2026 at 03:18:21PM +0100, pelzi@flying-snail.de wrote:
>> Package: linux-image-6.12.69+deb13-amd64
>> Version: 6.12.69-1
>> Severity: important
>> X-Debbugs-Cc: debian-amd64@lists.debian.org
>> User: debian-amd64@lists.debian.org
>> Usertags: amd64
>>
>> Dear Maintainer,
>>
>> after inclusion in mainline kernel, the module rtw_usb with its dependent
>> modules,
>> detected and initialized the USB wifi dongle with the followinig IDs:
>> idVendor=0bda, idProduct=a811, bcdDevice= 2.00
>>
>> This did work fine with the kernels installed from Debian stable linux-image up
>> to version 6.12.48-1.
>>
>> After upgrading to version 6.12.63-1, this module fails to identify the
>> device,
>> and upgrading again to version 6.12.69-1 does not cure the problem.
>>
>> The outcome of adding this wifi dongle with 6.12.63-1 or 6.12.69-1 are the
>> following
>> entries in dmesg:
>>   usb 1-7: USB disconnect, device number 6
>>   usb 1-7: new high-speed USB device number 8 using xhci_hcd
>>   usb 1-7: New USB device found, idVendor=0bda, idProduct=a811, bcdDevice= 2.00
>>   usb 1-7: New USB device strings: Mfr=1, Product=2, SerialNumber=3
>>   usb 1-7: Product: 802.11ac WLAN Adapter
>>   usb 1-7: Manufacturer: Realtek
>>   usb 1-7: SerialNumber: 00e04c000001
>>
>> No additional entries are generated in dmesg.
>>
>> The expected outcome are additional entries in dmesg like
>>   usbcore: registered new interface driver rtw_8821au
>>   usbcore: registered new interface driver rt2800usb
> Can you please provide a full kernel log for both the working and the
> broken kernel?
>
> Does the broken kernel emit anything to the kernel log when you plug in
> the dongle in the completely booted system?

Not sure what you mean with a full kernel log. A verbatim full kernel log of
the machine booting would be really big and I'm not sure how to identify and
mask sensitive information that could be contained within.

So let's start with what happens when unplugging and plugging the dongle on
the booted system with kernel 6.12.48 (i. e. the WORKING kernel):

$ uname -a
Linux athlon1 6.12.48+deb13-amd64 #1 SMP PREEMPT_DYNAMIC Debian 6.12.48-1
(2025-09-20) x86_64 GNU/Linux
$ sudo dmesg -W
[1108922.642771] usb 1-7: USB disconnect, device number 6
[1108925.446487] br0: port 2(wlx3c4937077611) entered disabled state
[1108925.447489] rtw_8821au 1-7:1.0 wlx3c4937077611 (unregistering): left
allmulticast mode
[1108925.447494] rtw_8821au 1-7:1.0 wlx3c4937077611 (unregistering): left
promiscuous mode
[1108925.447498] br0: port 2(wlx3c4937077611) entered disabled state
[1108925.748845] usb 1-7: new high-speed USB device number 17 using xhci_hcd
[1108925.885271] usb 1-7: New USB device found, idVendor=0bda, idProduct=a811,
bcdDevice= 2.00
[1108925.885288] usb 1-7: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[1108925.885296] usb 1-7: Product: 802.11ac WLAN Adapter
[1108925.885302] usb 1-7: Manufacturer: Realtek
[1108925.885308] usb 1-7: SerialNumber: 00e04c000001
[1108925.892318] rtw_8821au 1-7:1.0: Firmware version 42.4.0, H2C version 0
[1108926.326793] rtw_8821au 1-7:1.0 wlx3c4937077611: renamed from wlan0
^C

(after performing networkctl reconfigure <interface name>, the network is fully
functional again)

The equivalent action with kernel version 6.12.63-1 or 6.12.69-1 (the BROKEN
kernel) only produces:
usb 1-7: USB disconnect, device number 6
usb 1-7: new high-speed USB device number 8 using xhci_hcd
usb 1-7: New USB device found, idVendor=0bda, idProduct=a811, bcdDevice=
2.00 usb 1-7: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-7: Product: 802.11ac WLAN Adapter
usb 1-7: Manufacturer: Realtek
usb 1-7: SerialNumber: 00e04c000001
^C

So, you only seem to see the reaction of the usb subsystem, but no action from
any driver. This is exactly the same on boot, which is why you also do not see
any logs from a network subsystem.

> Best regards
> Uwe

Best regards,
Andreas.

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Bug#1127678: linux-image-6.12.69+deb13-amd64: Kernel module rtw_usb fails to detect usb wifi dongle with RTL8811AU chipset pelzi@flying-snail.de - 2026-05-04 00:10 +0200

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