From ae7ca950f236fd4e2ed850a561c56dec9d306b67 Mon Sep 17 00:00:00 2001
From: Seth Morabito <web@loomcom.com>
Date: Thu, 13 Apr 2023 05:56:35 +0200
Subject: [PATCH] 3B2: Fix for diagnostics timer hang

Under certain circumstances, the timer resolution in the Version 3
could become coarse enough that very short timer intervals would lead
to an infinite loop of bus errors when running timer firmware
diagnostics.
---
 3B2/3b2_timer.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/3B2/3b2_timer.c b/3B2/3b2_timer.c
index 3b2f515b..61955df2 100644
--- a/3B2/3b2_timer.c
+++ b/3B2/3b2_timer.c
@@ -92,9 +92,13 @@
 #define QUICK_DELAY 100
 #endif
 
-#define DELAY_US(C,N) ((TIMER_MODE(C) == 3) ?                \
-                       (TIME_BASE[(N)] * (C)->divider) / 2 : \
-                       TIME_BASE[(N)] * (C)->divider)
+#define MIN_US 100
+
+#define CALC_US(C,N) ((TIMER_MODE(C) == 3) ?      \
+                      (TIME_BASE[(N)] * (C)->divider) / 2 : \
+                      TIME_BASE[(N)] * (C)->divider)
+
+#define DELAY_US(C,N) (MAX(MIN_US, CALC_US((C),(N))))
 
 #if defined(REV3)
 /* Microseconds per step (Version 3 system board):