Linux 5.2 Staging Adds New Subsystem/Drivers Yet Is 111k Lines of Code Lighter
Written by Michael Larabel in Linux Kernel on 7 May 2019 at 06:54 PM EDT. 2 Comments
Linus Torvalds happily pulled in the staging subsystem updates today for the Linux 5.2 kernel. While new functionality was added to staging including two new "subsystems", the overall net change for the lines of code is being 111,641 lines of code less.

Among the major work to find within the kernel's staging/IIO area for Linux 5.2 are:

- The new Fieldbus subsystem around industrial automation/control systems. Fieldbus is used for connecting different systems/components/instruments within industrial environments. Fieldbus is used for connecting facilities ranging from manufacturing plants up to nuclear energy facilities.

- Another new subsystem/interface is a Generic Counters implementation to be used by different drivers for a generic counting infrastructure.

- A set of new drivers is the Daktronics code "kpc2000" for powering various scoreboards / video displays / digital billboards. This Daktronics code has been out-of-tree since the "Linux 2.x" days but is finally being mainlined in Linux 5.2 while the code is still being cleaned up.

Even with those big additions and a lot of smaller clean-ups and code improvements, the staging size still shrunk... There were 929 files changed and 22,720 lines of new code introduced but the code-base shrunk by 134,361 lines of code. Making that big net loss is the removal of the Realtek "RTLWIFI" driver from staging. As covered a few days ago, that Realtek WiFi driver is being succeeded by the new RTW88 WiFi Linux driver that with Linux 5.2 is being added to the formal networking subsystem. As a result, the RTLWIFI driver is being dropped. That new Realtek RTW88 driver is less than 50k lines of code in its current shape, so the kernel will still be lighter once that driver is merged in the days ahead.

The complete list of staging changes for Linux 5.2 can be found via this pull request.
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