The official Raspberry Pi touchscreen will be supported in the mainline Linux kernel, as this Wednesday pull request by Google engineer Dmitry Torokhov provides support for the 7-inch, 800 x 480 display. The touchscreen has existed for several years, though prior to now, support was provided either by customized kernels for distributions like Raspbian-which specifically targets the Raspberry Pi-or by custom kernel patching.
Though external displays typically do not require custom drivers, the Raspberry Pi touchscreen connects via the DSI port, rather than HDMI, with power provided via GPIO pins.
SEE: Inside the Raspberry Pi: The story of the $35 computer that changed the world (cover story PDF) (TechRepublic)
With the touchscreen for the Raspberry Pi, it is possible to make a DIY tablet, or a smart information display, among other projects.
For Arm-powered devices as a whole, the addition of Energy Aware Scheduling for 4.21 will increase battery life, taking full advantage of the big.LITTLE architecture for increased power efficiency. This new scheduler is designed to work with the topology of Arm processors with heterogeneous high-power and high-efficiency/low-power cores.
Other changes to Linux 4.21 include vast improvements to the AMDGPU driver, adding support for FreeSync and Adaptive-Sync. This allows for the use of variable frame rates for gaming, and fixed video frame rates for movies, as well as Adaptive Backlight Management (ABM) for power savings and increasing image quality and readability in low light conditions. Kernel 4.21 also brings support for ROCm GPU computing for Polaris and Vega 12 graphics processors.
Linux 4.21 also includes a 16×32 font for HiDPI displays, which will be helpful for users of laptops with 3K or 4K displays, as console messages at boot are quite difficult to see under standard font sizes for display panels with high pixel densities.
The big takeaways for tech leaders:
- The Official Raspberry Pi touchscreen will work out-of-the-box on distributions shipping version 4.21 of the Linux kernel.
- Improvements to task scheduling and graphics drivers provide increases to battery life on mobile devices, and performance improvement on GPUs.