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clk: vt8500: Fix device clock divisor calculations 

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>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
hifive-unleashed-5.1
Tony Prisk 2012-12-27 13:14:30 +13:00 committed by Mike Turquette
parent 35a5db55ab
commit 72480014b8
1 changed files with 8 additions and 0 deletions
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8
drivers/clk/clk-vt8500.c
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@ -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;