Messages in this thread Patch in this message | | | From | Tony Prisk <> | Subject | [PATCH 2/3] clk: vt8500: Fix device clock divisor calculations | Date | Thu, 27 Dec 2012 13:14:30 +1300 |
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When calculating device clock divisor values in set_rate and round_rate, we do a simple integer divide. If parent_rate / rate has a fraction, this is dropped which results in the device clock being set too high.
This patch corrects the problem by adding 1 to the calculated divisor if the division would have had a decimal result.
Signed-off-by: Tony Prisk <linux@prisktech.co.nz> --- drivers/clk/clk-vt8500.c | 8 ++++++++ 1 file changed, 8 insertions(+)
diff --git a/drivers/clk/clk-vt8500.c b/drivers/clk/clk-vt8500.c index 0cb26be..3306c2b 100644 --- a/drivers/clk/clk-vt8500.c +++ b/drivers/clk/clk-vt8500.c @@ -123,6 +123,10 @@ static long vt8500_dclk_round_rate(struct clk_hw *hw, unsigned long rate, struct clk_device *cdev = to_clk_device(hw); u32 divisor = *prate / rate; + /* If prate / rate would be decimal, incr the divisor */ + if (rate * divisor < *prate) + divisor++; + /* * If this is a request for SDMMC we have to adjust the divisor * when >31 to use the fixed predivisor @@ -141,6 +145,10 @@ static int vt8500_dclk_set_rate(struct clk_hw *hw, unsigned long rate, u32 divisor = parent_rate / rate; unsigned long flags = 0; + /* If prate / rate would be decimal, incr the divisor */ + if (rate * divisor < *prate) + divisor++; + if (divisor == cdev->div_mask + 1) divisor = 0; -- 1.7.9.5
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