tree b56c25c1ec7f4fd8cf082a16adedf3e5d945e30c
parent 1a0b2d0e7e8282d471b68e4abab51ca8600a2d71
author Weicai Yang <weicai@google.com> 1602718448 -0700
committer weicaiyang <49293026+weicaiyang@users.noreply.github.com> 1602795043 -0700

[uart/dv] Improve uart run time performace

spinwait consumes most of the sim time when uart freq is lowest and core
clk freq is highest.
Add spinwait_delay_ns to reduce the frequency of polling tx/rx_idle
It runs 4x faster with vcs in this case now

Signed-off-by: Weicai Yang <weicai@google.com>