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>
parent
b11d282d
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