tx4938ide: Avoid underflow on calculation of a wait cycle

Make 'wt' variable signed while it can be negative during calculation.

Suggested-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Cc: sshtylyov@ru.mvista.com
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/ide/tx4938ide.c b/drivers/ide/tx4938ide.c
index 796289cf97e..9120063e8f8 100644
--- a/drivers/ide/tx4938ide.c
+++ b/drivers/ide/tx4938ide.c
@@ -26,12 +26,13 @@ static void tx4938ide_tune_ebusc(unsigned int ebus_ch,
         unsigned int sp = (cr >> 4) & 3;
         unsigned int clock = gbus_clock / (4 - sp);
         unsigned int cycle = 1000000000 / clock;
-        unsigned int wt, shwt;
+        unsigned int shwt;
+        int wt;
 
         /* Minimum DIOx- active time */
         wt = DIV_ROUND_UP(t->act8b, cycle) - 2;
         /* IORDY setup time: 35ns */
-        wt = max(wt, DIV_ROUND_UP(35, cycle));
+        wt = max_t(int, wt, DIV_ROUND_UP(35, cycle));
         /* actual wait-cycle is max(wt & ~1, 1) */
         if (wt > 2 && (wt & 1))
                 wt++;