Messages in this thread Patch in this message | | | From | Haojian Zhuang <> | Subject | [PATCH] clk: factor: calculate rate by do_div | Date | Mon, 3 Dec 2012 16:14:37 +0800 |
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clk->rate = parent->rate / div * mult
The formula is OK. But it may overflow while we do operate with unsigned long. So use do_div instead.
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com> --- drivers/clk/clk-fixed-factor.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/clk-fixed-factor.c b/drivers/clk/clk-fixed-factor.c index a489985..1ef271e 100644 --- a/drivers/clk/clk-fixed-factor.c +++ b/drivers/clk/clk-fixed-factor.c @@ -28,8 +28,11 @@ static unsigned long clk_factor_recalc_rate(struct clk_hw *hw, unsigned long parent_rate) { struct clk_fixed_factor *fix = to_clk_fixed_factor(hw); + unsigned long long int rate; - return parent_rate * fix->mult / fix->div; + rate = (unsigned long long int)parent_rate * fix->mult; + do_div(rate, fix->div); + return (unsigned long)rate; } static long clk_factor_round_rate(struct clk_hw *hw, unsigned long rate, -- 1.7.10.4
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