Patch "clk: imx: fix integer overflow in AV PLL round rate" has been added to the 4.8-stable tree

This is a note to let you know that I've just added the patch titled

clk: imx: fix integer overflow in AV PLL round rate

to the 4.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
clk-imx-fix-integer-overflow-in-av-pll-round-rate.patch
and it can be found in the queue-4.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Emil Lundmark <[email protected]>
Date: Wed, 12 Oct 2016 12:31:40 +0200
Subject: clk: imx: fix integer overflow in AV PLL round rate

From: Emil Lundmark <[email protected]>

commit 5c2f117a22e46a4afee6ddee29b653a7a2a6b41f upstream.

Since 'parent_rate * mfn' may overflow 32 bits, the result should be stored using 64 bits.

The problem was discovered when trying to set the rate of the audio PLL (pll4_post_div) on an i.MX6Q. The desired rate was 196.608 MHz, but the actual rate returned was 192.000570 MHz. The round rate function should have been able to return 196.608 MHz, i.e., the desired rate.

---
 drivers/clk/imx/clk-pllv3.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

@@ -223,7 +223,7 @@ static unsigned long clk_pllv3_av_recalc
 	temp64 *= mfn;
 	do_div(temp64, mfd);
 
-	return (parent_rate * div) + (u32)temp64;
+	return parent_rate * div + (unsigned long)temp64;
 }
 
 static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate,

@@ -247,7 +247,11 @@ static long clk_pllv3_av_round_rate(stru
 	do_div(temp64, parent_rate);
 	mfn = temp64;
 
-	return parent_rate * div + parent_rate * mfn / mfd;
+	temp64 = (u64)parent_rate;
+	temp64 *= mfn;
+	do_div(temp64, mfd);
+
+	return parent_rate * div + (unsigned long)temp64;
 }
 
 static int clk_pllv3_av_set_rate(struct clk_hw *hw, unsigned long rate,

Patches currently in stable-queue which might be from [email protected] are

queue-4.8/clk-imx-fix-integer-overflow-in-av-pll-round-rate.patch