linux-kernel - [PATCH 1/3] clocksource: timer-dm: Check prescaler value

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Message-ID: <20180117214714.GB11952@lenoch>
Date:   Wed, 17 Jan 2018 22:47:14 +0100
From:   Ladislav Michl <ladis@...ux-mips.org>
To:     linux-omap@...r.kernel.org, linux-pwm@...r.kernel.org
Cc:     Keerthy <j-keerthy@...com>, daniel.lezcano@...aro.org,
        thierry.reding@...il.com, tony@...mide.com, aaro.koskinen@....fi,
        Claudiu.Beznea@...rochip.com, narmstrong@...libre.com,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        sebastian.reichel@...labora.co.uk, robh+dt@...nel.org,
        t-kristo@...com, grygorii.strashko@...com
Subject: [PATCH 1/3] clocksource: timer-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@...ux-mips.org>
---
 drivers/clocksource/timer-dm.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/clocksource/timer-dm.c b/drivers/clocksource/timer-dm.c
index 60db1734ea3b..324ec93d3dd2 100644
--- a/drivers/clocksource/timer-dm.c
+++ b/drivers/clocksource/timer-dm.c
@@ -663,13 +663,13 @@ int omap_dm_timer_set_prescaler(struct omap_dm_timer *timer, int prescaler)
 {
 	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;
 	}