[PATCH] clk: imx: Fix fractional clock set rate computation

From: Abel Vesa
Date: Fri Jan 18 2019 - 07:54:20 EST


Before multiplying by PLL_FRAC_DENOM, the temp64 needs to be
temp64 = rate * 2 - divfi * parent_rate * 8, instead of:
temp64 = (rate * 2 - divfi) * parent_rate

Fixes: 6209624b9a5c1e ("clk: imx: Add fractional PLL output clock")
Signed-off-by: Abel Vesa <abel.vesa@xxxxxxx>
---
drivers/clk/imx/clk-frac-pll.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/imx/clk-frac-pll.c b/drivers/clk/imx/clk-frac-pll.c
index 0026c39..76b9eb1 100644
--- a/drivers/clk/imx/clk-frac-pll.c
+++ b/drivers/clk/imx/clk-frac-pll.c
@@ -155,13 +155,14 @@ static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
{
struct clk_frac_pll *pll = to_clk_frac_pll(hw);
u32 val, divfi, divff;
- u64 temp64 = parent_rate;
+ u64 temp64;
int ret;

parent_rate *= 8;
rate *= 2;
divfi = rate / parent_rate;
- temp64 *= rate - divfi;
+ temp64 = parent_rate * divfi;
+ temp64 = rate - temp64;
temp64 *= PLL_FRAC_DENOM;
do_div(temp64, parent_rate);
divff = temp64;
--
2.7.4