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| author |   Anson Huang <b20788@freescale.com> | 2016-06-08 22:33:31 +0800 |
|---|---|---|
| committer |   Shawn Guo <shawnguo@kernel.org> | 2016-06-12 19:25:38 +0800 |
| commit | ba7f4f557eb67ee21c979c8539dc1886f5d5341c (patch) | |
| tree | 48739eaba18d4f0c57bf1dcc8b4aa13d9ec28382 /drivers/clk/imx | |
| parent | Linux 4.7-rc1 (diff) | |
| download | linux-dev-ba7f4f557eb67ee21c979c8539dc1886f5d5341c.tar.xz linux-dev-ba7f4f557eb67ee21c979c8539dc1886f5d5341c.zip | |
clk: imx: correct AV PLL rate formula
The audio/video PLL's rate calculation is as below in RM:
Fref * (DIV_SELECT + NUM / DENOM), in origin 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
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 overflow
a 32 bit value, 64 bit value should be used.
After updating this formula, the dram PLL's rate is
1066MHz, which is correct, while the old formula gets
1056MHz.
[Aisheng: fix clk_pllv3_av_round_rate too]
Signed-off-by: Anson Huang <b20788@freescale.com>
Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
Diffstat (limited to 'drivers/clk/imx')
| -rw-r--r-- | drivers/clk/imx/clk-pllv3.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/clk/imx/clk-pllv3.c b/drivers/clk/imx/clk-pllv3.c index 4826b3c9e19e..2afc677979a3 100644 --- a/drivers/clk/imx/clk-pllv3.c +++ b/drivers/clk/imx/clk-pllv3.c @@ -218,8 +218,12 @@ 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 = (u64)parent_rate; - return (parent_rate * div) + ((parent_rate / mfd) * mfn); + temp64 *= mfn; + do_div(temp64, mfd); + + return (parent_rate * div) + (u32)temp64; } static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate, @@ -243,7 +247,7 @@ 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 / mfd * mfn; + return parent_rate * div + parent_rate * mfn / mfd; } static int clk_pllv3_av_set_rate(struct clk_hw *hw, unsigned long rate, |