Linux 5.20 To Feature Faster Console Scrolling At Boot For Old FBDEV Drivers

This week's DRM-Misc-Next pull request was sent out of new DRM changes ready for queuing ahead of Linux 5.20. There isn't too much to get excited about for this week's code updates going to DRM-Next, but there is "fbcon: Improve scrolling performance" that did get my attention.

This scrolling performance work for the frame-buffer console (FBCON) it turns out is aimed at improving the scrolling performance at boot time. The change is targeted at improving the frame-buffer device (FBDEV) scrolling performance while a logo is shown (such as is commonly the case for showing the Tux logo) amid the boot messages for those not using a graphical boot splash setup like Plymouth.

This optimization for Linux 5.20 doesn't improve the performance if using a DRM driver with FBCON but rather for those still relying on an accelerated FBDEV driver.

FBDEV maintainer summarized the difference with this scrolling performance improvement as, "if you run an accelerated fbdev driver and have FRAMEBUFFER_CONSOLE_LEGACY_ACCELERATION enabled, console scrolling is slowed down by factors so that it feels as if you use a 9600 baud terminal. So, drop those unnecessary checks and speed up fbdev console acceleration during bootup."

Outside of the scrolling performance at boot, this change doesn't appear to have any other impact. This scrolling optimization and changes to the smaller Direct Rendering Manager drivers is part of this week's drm-misc-next pull.