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tx4938ide: Avoid underflow on calculation of a wait cycle

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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>
This commit is contained in:
Atsushi Nemoto 2008-11-02 21:40:10 +01:00 committed by Bartlomiej Zolnierkiewicz
parent 9d4eb0a33e
commit 7afa05350c
1 changed files with 3 additions and 2 deletions
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5
drivers/ide/tx4938ide.c
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@ -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++;