Cortex-A9 delay() shorten rarely

[Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>]

Hi,

I am testing NetBSD on Cortex-A9 development board. I found delay()
shorten rarely.

I found below patch fix this issue.
====================
diff --git a/sys/arch/arm/arm32/cortex_pmc.c b/sys/arch/arm/arm32/cortex_pmc.c
index 277c272..16c9cc6 100644
--- a/sys/arch/arm/arm32/cortex_pmc.c
+++ b/sys/arch/arm/arm32/cortex_pmc.c
@@ -103,7 +103,7 @@ delay(u_int arg)
                if (ctrl & CORTEX_CNTOFL_C) {
                  /* Reset overflow flag for cycle counter in overflow register */
                        armreg_pmovsr_write(CORTEX_CNTOFL_C);
-                       delta += (last + (counts_per_wrap - cur));
+                       delta += (cur + (counts_per_wrap - last));
                } else {
                        delta += (cur - last);
                }
====================

Could you comment this patch?
If there is no objection, I will commit this patch after a few days.


Thanks,

-- 
//////////////////////////////////////////////////////////////////////
Internet Initiative Japan Inc.

Device Engineering Section,
Core Product Development Department,
Product Division,
Technology Unit

Kengo NAKAHARA <k-nakahara%iij.ad.jp@localhost>