Linux 6.4 Spring Cleaning: Ditching Two Old USB Drivers

The USB/Thunderbolt changes were merged last week for the Linux 6.4 kernel and it ended up being a net reduction in the number of lines of code as a result of ditching two outdated USB drivers.

The USB/Thunderbolt changes for Linux 6.4 included new hardware support, various XHCI and DWC3 driver fixes, and other mostly small changes with no particular additions really jumping out on the change-log.

Greg Kroah-Hartman noted in the USB pull request that the "biggest" change this cycle is the removal of two obsolete drivers. Chopped out of Linux 6.4 were the u132-hcd and ftdi-elan to in turn lighten the kernel by a few thousand lines of code.

The ftdi-elan driver was dropped as it hadn't received any maintenance in several years and has a mix of trivial and harder set of known issues against the driver. Plus with the affected hardware being rare these days, the assumption is on the driver being unused by modern Linux systems. The fdti-elan driver is for the Elan Digital System's Uxxx adapters of USB to CardBus adapters. This driver was originally written back during the Linux 2.6 kernel days.

The other driver dropped this cycle is the u132-hcd driver, which again is for CardBus to USB adapters. The last actual change to this driver is reported to have been in 2006 and is unlikely there are any users of this driver/hardware running modern Linux 6.x kernels.

So dropping these CardBus to USB adapters is about time given no one maintaining the code for years and there being no expressed users. Also for Linux 6.4 over in the char/misc area, the char PCMCIA drivers were also dropped for Linux 6.4. Linux kernel spring cleaning at work; the full list of USB patches this cycle can be found via Greg's pull request that has since been merged to mainline.