Now that U-Boot has a background-processing feature, it is possible to reduce the amount of 'foreground' syncing of the display. At present this happens quite often.
Foreground syncing blocks all other processing, sometimes for 10ms or more. When pasting commands into U-Boot over the UART, this typically result in characters being dropped. For example, on rpi_4 it isn't possible to paste in more than 35 characters before things fail. This makes updating the environment or entering long commands very painful over the console, since text must be pasted in chunks, or the vidconsole device must be dropped from stdout.
This series introduces background syncing, enabled by default for boards which use video. The sync rates for foreground and background are configurable.
With this series it is possible to paste in any amount of text to the command line. Some sandbox-specific workarounds can now be removed and sandbox video (./u-boot -Dl) is significantly more responsive.
This obviously increases code size, since it enables a subsystem not normally used by default. However it only applies to boards which have VIDEO enabled, which are presumably less worried about memory space since the video code is fairly large.
Also it is possible to disable CMD_CYCLIC and reduce the growth to:
aarch64: (for 1/1 boards) all +1081.0 rodata +65.0 text +1016.0 arm: (for 1/1 boards) all +945.0 rodata +65.0 text +880.0
Without that, the increase doubles.
It is of course possible to disable CYCLIC and still use VIDEO but this reverts to the current behaviour
Changes in v2: - Add an SPL_CYCLIC symbol - Add a lot more explanation about the header files - Expand help for CONFIG_VIDEO - Fix 'groth' and 'work-around' typos in cover letter
Simon Glass (5): cyclic: Add a symbol for SPL video: Move last_sync to private data video: Use cyclic to handle video sync sandbox: Increase cyclic CPU-time limit sandbox: Drop video-sync in serial driver
common/Kconfig | 9 ++++++ common/Makefile | 2 +- drivers/serial/sandbox.c | 2 -- drivers/video/Kconfig | 35 +++++++++++++++++++++ drivers/video/video-uclass.c | 52 +++++++++++++++++++++++++------ drivers/watchdog/Kconfig | 1 + include/asm-generic/global_data.h | 2 +- include/cyclic.h | 6 ++-- include/video.h | 2 ++ 9 files changed, 96 insertions(+), 15 deletions(-)