clocksource: timer-ti-dm: Check prescaler value

Invalid value silently disables use of the prescaler.
Use -1 explicitely for that purpose and error out on
invalid value.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/clocksource/timer-ti-dm.c b/drivers/clocksource/timer-ti-dm.c
index 6abe5ab553ce..4cce6b224b87 100644
--- a/drivers/clocksource/timer-ti-dm.c
+++ b/drivers/clocksource/timer-ti-dm.c
@@ -663,13 +663,13 @@ static int omap_dm_timer_set_prescaler(struct omap_dm_timer *timer,
 {
         u32 l;
 
-        if (unlikely(!timer))
+        if (unlikely(!timer) || prescaler < -1 || prescaler > 7)
                 return -EINVAL;
 
         omap_dm_timer_enable(timer);
         l = omap_dm_timer_read_reg(timer, OMAP_TIMER_CTRL_REG);
         l &= ~(OMAP_TIMER_CTRL_PRE | (0x07 << 2));
-        if (prescaler >= 0x00 && prescaler <= 0x07) {
+        if (prescaler >= 0) {
                 l |= OMAP_TIMER_CTRL_PRE;
                 l |= prescaler << 2;
         }