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

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.

Fixes: ba7f4f557e ("clk: imx: correct AV PLL rate formula")
Cc: Anson Huang <b20788@freescale.com>
Signed-off-by: Emil Lundmark <emil@limesaudio.com>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Acked-by: Shawn Guo <shawnguo@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
This commit is contained in:
Emil Lundmark 2016-10-12 12:31:40 +02:00 committed by Stephen Boyd
parent 06b113e9f2
commit 5c2f117a22
1 changed files with 6 additions and 2 deletions
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8
drivers/clk/imx/clk-pllv3.c
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@ -223,7 +223,7 @@ static unsigned long clk_pllv3_av_recalc_rate(struct clk_hw *hw,
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(struct clk_hw *hw, unsigned long rate,
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,