This post outlines how I backported rtl8812au-dkms from Ubuntu Focal for Debian Buster and added support for the TP-Link Archer T4U v2 card to it. If you are only interested in the resulting .deb file skip to the end.
The TP-Link Archer T4U v2 is an AC1300 WiFi USB adapter. TP-Link provides drivers but they are built only for old kernel versions (<=3.19) and do not supoort DKMS, which makes upgrading a hassle.
Ubuntu provides the rtl8812au-dkms package which support the chipset in the Archer T4Uv2, but it doesn’t recognize the TP-Link product. So I set out to backport it to Debian Buster and make it support the Archer T4Uv2.
We start by fetching the rtl8812au source package from Ubuntu.
$ dget --allow-unauthenticated http://archive.ubuntu.com/ubuntu/pool/universe/r/rtl8812au/rtl8812au_4.3.8.12175.20140902+dfsg-0ubuntu12.dsc
$ cd rtl8812au-4.3.8.12175.20140902+dfsg/
$ sed -i s/dh-modaliases// debian/control
$ sed -i s/,modaliases// debian/rules
$ mk-build-deps ./debian/control --install --root-cmd sudo --remove
The sed lines remove reference to the dh-modaliases build dependency which Debian doesn’t have. I’m not really sure why they needed it for this package, but removing it didn’t hurt.
Next we add a new patch using quilt to support the Archer T4Uv2. We extract the 2357:010d USB vid:pid pair of the adapter using lsusb.
$ quilt push -a
$ quilt new add_archer_t4uv2.patch
$ quilt add os_dep/linux/usb_intf.c
$ vim os_dep/linux/usb_intf.c
The change we’ll be making to os_dep/linux/usb_intf.c is outlined by the following patch:
--- rtl8812au-4.3.8.12175.20140902+dfsg.orig/os_dep/linux/usb_intf.c
+++ rtl8812au-4.3.8.12175.20140902+dfsg/os_dep/linux/usb_intf.c
@@ -303,6 +303,7 @@ static struct usb_device_id rtw_usb_id_t
{USB_DEVICE(0x20f4, 0x805b),.driver_info = RTL8812}, /* TRENDnet - */
{USB_DEVICE(0x2357, 0x0101),.driver_info = RTL8812}, /* TP-Link - Archer T4U */
{USB_DEVICE(0x2357, 0x0103),.driver_info = RTL8812}, /* TP-Link - Archer T4UH */
+ {USB_DEVICE(0x2357, 0x010d),.driver_info = RTL8812}, /* TP-Link - Archer T4Uv2 */
{USB_DEVICE(0x0411, 0x025d),.driver_info = RTL8812}, /* Buffalo - WI-U3-866D */
#endif
Finish up adding the patch:
$ quilt header --dep3 -e
$ quilt refresh
$ quilt pop -a
And build the package:
$ DEBEMAIL="Guy Rutenberg <guyrutenberg@gmail.com>" debchange --bpo
$ debuild -us -uc
Now we can install the newly created deb package:
$ cd ../
$ sudo apt install ./rtl8812au-dkms_4.3.8.12175.20140902+dfsg-0ubuntu12~bpo10+1_all.deb
If you came here only for the actual binary package you can find it in my deb repository: https://guyrutenberg.com/debian/buster/