Commit ba7f4f55 authored by Anson Huang's avatar Anson Huang Committed by Shawn Guo

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: default avatarAnson Huang <b20788@freescale.com>
Signed-off-by: default avatarDong Aisheng <aisheng.dong@nxp.com>
Signed-off-by: default avatarShawn Guo <shawnguo@kernel.org>
parent 1a695a90
...@@ -218,8 +218,12 @@ static unsigned long clk_pllv3_av_recalc_rate(struct clk_hw *hw, ...@@ -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 mfn = readl_relaxed(pll->base + PLL_NUM_OFFSET);
u32 mfd = readl_relaxed(pll->base + PLL_DENOM_OFFSET); u32 mfd = readl_relaxed(pll->base + PLL_DENOM_OFFSET);
u32 div = readl_relaxed(pll->base) & pll->div_mask; 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, 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, ...@@ -243,7 +247,7 @@ static long clk_pllv3_av_round_rate(struct clk_hw *hw, unsigned long rate,
do_div(temp64, parent_rate); do_div(temp64, parent_rate);
mfn = temp64; 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, static int clk_pllv3_av_set_rate(struct clk_hw *hw, unsigned long rate,
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment