linux-kernel - [PATCH] lis3lv02d: Avoid zero-division

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Date:	Thu, 03 Nov 2011 13:09:00 +0100
From:	Takashi Iwai <tiwai@...e.de>
To:	Eric Piel <eric.piel@...mplin-utc.net>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] lis3lv02d: Avoid zero-division

In some weird situation, HP DriveGuard chip can't read ODR value
correctly, and it results in a zero-division Oops in lis3lv02d driver.
This patch fixes the Oops by checking the value appopriately, and skips
if any weird value is read.

Cc: <stable@...nel.org>
Signed-off-by: Takashi Iwai <tiwai@...e.de>
---
 drivers/misc/lis3lv02d/lis3lv02d.c |   14 +++++++++++---
 1 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/lis3lv02d/lis3lv02d.c b/drivers/misc/lis3lv02d/lis3lv02d.c
index 8b51cd6..c4eb2f3 100644
--- a/drivers/misc/lis3lv02d/lis3lv02d.c
+++ b/drivers/misc/lis3lv02d/lis3lv02d.c
@@ -228,6 +228,14 @@ static int lis3lv02d_set_odr(int rate)
 	return -EINVAL;
 }
 
+static void lis3lv02d_power_delay(struct lis3lv02d *lis3)
+{
+	int odr = lis3lv02d_get_odr();
+	if (odr <= 0)
+		return;
+	msleep(lis3->pwron_delay / odr);
+}
+
 static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3])
 {
 	u8 ctlreg, reg;
@@ -266,7 +274,7 @@ static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3])
 
 	lis3->read(lis3, ctlreg, &reg);
 	lis3->write(lis3, ctlreg, (reg | selftest));
-	msleep(lis3->pwron_delay / lis3lv02d_get_odr());
+	lis3lv02d_power_delay(lis3);
 
 	/* Read directly to avoid axis remap */
 	x = lis3->read_data(lis3, OUTX);
@@ -275,7 +283,7 @@ static int lis3lv02d_selftest(struct lis3lv02d *lis3, s16 results[3])
 
 	/* back to normal settings */
 	lis3->write(lis3, ctlreg, reg);
-	msleep(lis3->pwron_delay / lis3lv02d_get_odr());
+	lis3lv02d_power_delay(lis3);
 
 	results[0] = x - lis3->read_data(lis3, OUTX);
 	results[1] = y - lis3->read_data(lis3, OUTY);
@@ -385,7 +393,7 @@ void lis3lv02d_poweron(struct lis3lv02d *lis3)
 	}
 
 	/* LIS3 power on delay is quite long */
-	msleep(lis3->pwron_delay / lis3lv02d_get_odr());
+	lis3lv02d_power_delay(lis3);
 
 	if (lis3->reg_ctrl)
 		lis3_context_restore(lis3);
-- 
1.7.7

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