The TSC rate is empirically swinging during early boot. That
leaves timestamps and udelay()s to not be correct. To rectify this
stop using TSC for all of these time sources. Instead use the
performance TSC which is at a fixed 100MHz clock. That provides
stable time sources and legit timestamps.
BUG=b:72378235,b:72170796
Change-Id: Ia2693c415c557aac687bcb48ee69358ea1c53d67
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/23424
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Furquan Shaikh <furquan@google.com>
The TSC has been observed to be ticking at a non-constant rate
in early boot. The root cause is still not known, but this
misbehavior necessitates an alternative monotonic timer source.
Use the perf TSC which ticks at 100 MHz. This also means the
timestamp table is not accurate as well. Root cause of TSC rate
instability needs to be resolved in order to fix that.
BUG=b:72170796
Change-Id: Ie052169868a9d9f25f8cc0ce8dd8251b560e671f
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/23397
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Justin TerAvest <teravest@chromium.org>
