[RFC PATCH 2/5] clk: Introduce 'clk_round_rate_nearest()'

[u.kleine-koenig@pengutronix.de (Uwe Kleine-König)]

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

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