[PATCH] ARM: imx: correct Audio/Video PLL rate calculation formula

[Anson Huang]

The audio/video PLL's rate calculation formula is as below in RM:

Fref * (DIV_SELECT + NUM / DENOM),

in original clk-pllv3's code, below code is used:

(parent_rate * div) + ((parent_rate / mfd) * mfn

as it does NOT consider the float data using div, so below
calculation formula should be used as a decent method:

(parent_rate * div) + ((parent_rate * mfn) / mfd)

and we also need to consider parent_rate * mfd may exceed
a 32 bit value, 64 bit value should be used.

Signed-off-by: Anson Huang <b20788 at freescale.com>
---
 arch/arm/mach-imx/clk-pllv3.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-imx/clk-pllv3.c b/arch/arm/mach-imx/clk-pllv3.c
index 641ebc5..f83cf0d 100644
--- a/arch/arm/mach-imx/clk-pllv3.c
+++ b/arch/arm/mach-imx/clk-pllv3.c
@@ -203,8 +203,12 @@ static unsigned long clk_pllv3_av_recalc_rate(struct clk_hw *hw,
 	u32 mfn = readl_relaxed(pll->base + PLL_NUM_OFFSET);
 	u32 mfd = readl_relaxed(pll->base + PLL_DENOM_OFFSET);
 	u32 div = readl_relaxed(pll->base) & pll->div_mask;
+	u64 temp64 = parent_rate;
 
-	return (parent_rate * div) + ((parent_rate / mfd) * mfn);
+	temp64 *= mfn;
+	do_div(temp64, mfd);
+
+	return (parent_rate * div) + temp64;
 }
 
 static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate,
-- 
1.9.1