linux-kernel - [PATCH 4.0 153/220] ASoC: pcm512x: Fix divide by zero issue

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Message-Id: <20150502185900.945460599@linuxfoundation.org>
Date:	Sat,  2 May 2015 21:01:08 +0200
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Howard Mitchell <hm@...edded.co.uk>,
	Mark Brown <broonie@...ena.org.uk>
Subject: [PATCH 4.0 153/220] ASoC: pcm512x: Fix divide by zero issue

4.0-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Howard Mitchell <hm@...edded.co.uk>

commit f073faa73626f41db7050a69edd5074c53ce6d6c upstream.

If den=1 and pllin_rate>20MHz then den and num are adjusted to 0
causing a divide by zero error a few lines further on. Therefore
this patch correctly scales num and den such that
pllin_rate/den < 20MHz as required in the device data sheet.

Signed-off-by: Howard Mitchell <hm@...edded.co.uk>
Signed-off-by: Mark Brown <broonie@...ena.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/soc/codecs/pcm512x.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/sound/soc/codecs/pcm512x.c
+++ b/sound/soc/codecs/pcm512x.c
@@ -576,8 +576,8 @@ static int pcm512x_find_pll_coeff(struct
 
 	/* pllin_rate / P (or here, den) cannot be greater than 20 MHz */
 	if (pllin_rate / den > 20000000 && num < 8) {
-		num *= 20000000 / (pllin_rate / den);
-		den *= 20000000 / (pllin_rate / den);
+		num *= DIV_ROUND_UP(pllin_rate / den, 20000000);
+		den *= DIV_ROUND_UP(pllin_rate / den, 20000000);
 	}
 	dev_dbg(dev, "num / den = %lu / %lu\n", num, den);
 


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