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Subject[PATCH 2/3] clk: vt8500: Fix device clock divisor calculations
Date
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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