[commit] r1811 - cpu/x86/pc/olpc

[repository service]

Author: wmb
Date: Tue May 18 01:31:18 2010
New Revision: 1811
URL: http://tracker.coreboot.org/trac/openfirmware/changeset/1811

Log:
OLPC trac 10146 - fixed reliability problem with ISA timer selftest.

Modified:
   cpu/x86/pc/olpc/timertest.fth

Modified: cpu/x86/pc/olpc/timertest.fth
==============================================================================
--- cpu/x86/pc/olpc/timertest.fth	Tue May 18 00:42:46 2010	(r1810)
+++ cpu/x86/pc/olpc/timertest.fth	Tue May 18 01:31:18 2010	(r1811)
@@ -3,9 +3,13 @@

dev /isa/timer

+\ "0 count@" takes 4.5 uS on XO-1 and 6.3 uS on XO-1.5, due to the
+\ several I/O port accesses involved.  That is longer than the per-count
+\ time, so the test for rollover needs some slop ("5 <") because you can't
+\ depend on being able to see any specific value.
 : wait-rollover  ( -- error? )
-   get-msecs  d# 200 +   begin   ( time-limit )
-      0 count@ 1 =  if  drop false exit  then
+   get-msecs  d# 100 +   begin   ( time-limit )
+      0 count@  5 <  if  drop false exit  then
       dup get-msecs -            ( time-limit diff )
    0<= until
    drop true
@@ -20,14 +24,19 @@
       then
    then

-   wait-rollover  if
+   lock[  wait-rollover  if
+      ]unlock
       ." The ISA PIT timer did not reach a count of 1."  cr
       true exit
    then

-   1 ms
+   \ Ensure that rollover has completed so the first count below
+   \ is higher than the second count (the counter counts down).
+   d# 10 us

-   0 count@  d# 10000 d# 11000 between  0=  if
+   0 count@  1 ms  0 count@  ]unlock  -   ( delta-ticks )
+
+   d# 1150 d# 1250 between  0=  if  \ Nominal delta is 1199
       ." The ISA PIT timer is ticking at the wrong rate." cr
       true exit
    then