linux-kernel - v4.9-rc1: smiapp divides by zero

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Message-ID: <20161023102213.GA13705@amd>
Date:   Sun, 23 Oct 2016 12:22:13 +0200
From:   Pavel Machek <pavel@....cz>
To:     Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
Cc:     sakari.ailus@....fi, sre@...nel.org, pali.rohar@...il.com,
        linux-media@...r.kernel.org, galak@...eaurora.org,
        mchehab@....samsung.com, linux-kernel@...r.kernel.org
Subject: v4.9-rc1: smiapp divides by zero

Hi!

I tried to update camera code on n900 to v4.9-rc1, and I'm getting
some divide by zero, that eventually cascades into fcam-dev not
working.

mul is zero in my testing, resulting in divide by zero.

(Note that this is going from my patched camera-v4.8 tree to
camera-v4.9 tree.)

Best regards,
								Pavel

diff --git a/drivers/media/i2c/smiapp-pll.c b/drivers/media/i2c/smiapp-pll.c
index 5ad1edb..e0a6edd 100644
--- a/drivers/media/i2c/smiapp-pll.c
+++ b/drivers/media/i2c/smiapp-pll.c
@@ -16,6 +16,8 @@
  * General Public License for more details.
  */
 
+#define DEBUG
+
 #include <linux/device.h>
 #include <linux/gcd.h>
 #include <linux/lcm.h>
@@ -457,6 +459,10 @@ int smiapp_pll_calculate(struct device *dev,
 	i = gcd(pll->pll_op_clk_freq_hz, pll->ext_clk_freq_hz);
 	mul = div_u64(pll->pll_op_clk_freq_hz, i);
 	div = pll->ext_clk_freq_hz / i;
+	if (!mul) {
+		dev_err(dev, "forcing mul to 1\n");
+		mul = 1;
+	}
 	dev_dbg(dev, "mul %u / div %u\n", mul, div);
 
 	min_pre_pll_clk_div =

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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