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authorTomi Valkeinen <tomi.valkeinen@ti.com>2014-02-13 12:04:00 +0200
committerMike Turquette <mturquette@linaro.org>2014-02-26 18:23:58 -0800
commit7e50e7e176634e8cc0335778915be75df41043dc (patch)
treed89e206488b084af24d3336ed2ff42320e0b97c2 /drivers/clk/ti
parentb11d282dbea27db1788893115dfca8a7856bf205 (diff)
downloadlinux-7e50e7e176634e8cc0335778915be75df41043dc.tar.bz2
clk: ti/divider: fix rate calculation for fractional rates
ti/clk-divider.c does not calculate the rates consistently at the moment. As an example, on OMAP3 we have a clock divider with a source clock of 864000000 Hz. With dividers 6, 7 and 8 the theoretical rates are: 6: 144000000 7: 123428571.428571... 8: 108000000 Calling clk_round_rate() with the rate in the first column will give the rate in the second column: 144000000 -> 144000000 143999999 -> 123428571 123428572 -> 123428571 123428571 -> 108000000 Note how clk_round_rate() returns 123428571 for rates from 123428572 to 143999999, which is mathematically correct, but when clk_round_rate() is called with 123428571, the returned value is surprisingly 108000000. This means that the following code works a bit oddly: rate = clk_round_rate(clk, 123428572); clk_set_rate(clk, rate); As clk_set_rate() also does clock rate rounding, the result is that the clock is set to the rate of 108000000, not 123428571 returned by the clk_round_rate. This patch changes the ti/clk-divider.c to use DIV_ROUND_UP when calculating the rate. This gives the following behavior which fixes the inconsistency: 144000000 -> 144000000 143999999 -> 123428572 123428572 -> 123428572 123428571 -> 108000000 Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com> Signed-off-by: Mike Turquette <mturquette@linaro.org>
Diffstat (limited to 'drivers/clk/ti')
-rw-r--r--drivers/clk/ti/divider.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/drivers/clk/ti/divider.c b/drivers/clk/ti/divider.c
index a15e445570b2..e6aa10db7bba 100644
--- a/drivers/clk/ti/divider.c
+++ b/drivers/clk/ti/divider.c
@@ -112,7 +112,7 @@ static unsigned long ti_clk_divider_recalc_rate(struct clk_hw *hw,
return parent_rate;
}
- return parent_rate / div;
+ return DIV_ROUND_UP(parent_rate, div);
}
/*
@@ -182,7 +182,7 @@ static int ti_clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,
}
parent_rate = __clk_round_rate(__clk_get_parent(hw->clk),
MULT_ROUND_UP(rate, i));
- now = parent_rate / i;
+ now = DIV_ROUND_UP(parent_rate, i);
if (now <= rate && now > best) {
bestdiv = i;
best = now;
@@ -205,7 +205,7 @@ static long ti_clk_divider_round_rate(struct clk_hw *hw, unsigned long rate,
int div;
div = ti_clk_divider_bestdiv(hw, rate, prate);
- return *prate / div;
+ return DIV_ROUND_UP(*prate, div);
}
static int ti_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
@@ -216,7 +216,7 @@ static int ti_clk_divider_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long flags = 0;
u32 val;
- div = parent_rate / rate;
+ div = DIV_ROUND_UP(parent_rate, rate);
value = _get_val(divider, div);
if (value > div_mask(divider))