[U-Boot] [PATCH] timer: Fix possible underflow in udelay

[Andrew F. Davis <afd@ti.com>]

When the inputed usec is too large we process it in chunks of
CONFIG_WD_PERIOD size. Subtracting this from usec until usec is
zero. If usec is not an integer multiple of CONFIG_WD_PERIOD it
will underflow and the condition will not become false when it
should. Fix this logic.

Signed-off-by: Andrew F. Davis <afd@ti.com>
---
 lib/time.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lib/time.c b/lib/time.c
index f37150f..4ec3cb9 100644
--- a/lib/time.c
+++ b/lib/time.c
@@ -145,14 +145,14 @@ void __weak __udelay(unsigned long usec)
 
 void udelay(unsigned long usec)
 {
-	ulong kv;
+	ulong kv = usec > CONFIG_WD_PERIOD ? CONFIG_WD_PERIOD : usec;
+	ulong elapsed = 0;
 
 	do {
 		WATCHDOG_RESET();
-		kv = usec > CONFIG_WD_PERIOD ? CONFIG_WD_PERIOD : usec;
-		__udelay (kv);
-		usec -= kv;
-	} while(usec);
+		__udelay(kv);
+		elapsed += kv;
+	} while (elapsed < usec);
 }
 
 void mdelay(unsigned long msec)
-- 
2.9.3