Messages in this thread | | | Date | Sun, 16 Dec 2012 00:42:26 +0800 | Subject | Re: [PATCH] clk: factor: calculate rate by do_div | From | Haojian Zhuang <> |
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On Tue, Dec 4, 2012 at 9:32 AM, Haojian Zhuang <haojian.zhuang@gmail.com> wrote: > On Mon, Dec 3, 2012 at 4:14 PM, Haojian Zhuang <haojian.zhuang@gmail.com> wrote: >> 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 >> > > Correct Mike's email address.
Any comments? It's the bug what needs to be fixed.
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