Commits
Geert Uytterhoeven committed c531fb27e96
ARM: shmobile: timer: Fix preset_lpj leading to too short delays
On all shmobile ARM SoCs, loop-based delays may complete early, which
can be after only 1/3 (Cortex A9) or 1/2 (Cortex A7 or A15) of the
minimum required time.
This is caused by calculating preset_lpj based on incorrect assumptions
about the number of clock cycles per loop:
- All of Cortex A7, A9, and A15 run __loop_delay() at 1 loop per
CPU clock cycle,
- As of commit 11d4bb1bd067f9d0 ("ARM: 7907/1: lib: delay-loop: Add
align directive to fix BogoMIPS calculation"), Cortex A8 runs
__loop_delay() at 1 loop per 2 instead of 3 CPU clock cycles.
On SoCs with Cortex A7 and/or A15 CPU cores, this went unnoticed, as
delays use the ARM arch timer if available. R-Car Gen2 doesn't work if
the arch timer is disabled. However, APE6 can be used without the arch
timer.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>