Hello,

On Mon, May 19, 2014 at 10:29:05AM -0700, S?ren Brinkmann wrote:

With the improvements suggested by you I have this now:

long clk_round_rate_nearest(struct clk *clk, unsigned long rate)
{
	unsigned long lower, upper;

	lower = clk_round_rate(clk, rate);
	if (lower >= rate)
		return lower;

	upper = clk_round_rate(clk, rate + (rate - lower) - 1);
	if (upper == lower)
		return upper;

	lower = rate + 1;
	while (lower < upper) {
		unsigned long rounded, mid;

		mid = lower + ((upper - lower) >> 1);
		rounded = clk_round_rate(clk, mid);
		if (rounded < lower)
			lower = mid + 1;
		else
			upper = rounded;
	}

	return upper;
}

This is nearly my version now. I just lacks the overflow check when
calculating upper and I skipped the early return if (upper == lower).
(Instead the while condition evaluates to false on the first hit and
returns with the same result.)

Other than that I added a few comments. :-)

Something we still should resolve is the return type. It should match
clk_round_rate, but should both be signed or unsigned? 

Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |