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Commit 0e2de78e authored by Maxime COQUELIN's avatar Maxime COQUELIN Committed by Mike Turquette
Browse files

clk: divider: Optimize clk_divider_bestdiv loop 



Currently, the for-loop used to try all the different dividers to find the
one that best fit tries all the values from 1 to max_div, incrementing by one.
In case of power-of-two, or table based divider, the loop isn't optimal.

Instead of incrementing by one, this patch provides directly the next divider.

Signed-off-by: default avatarMaxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent 774b5143

drivers/clk/clk-divider.c

+13 −1
Original line number Diff line number Diff line
@@ -240,6 +240,18 @@ static bool _is_best_div(struct clk_divider *divider, 
	return now <= rate && now > best;

}



static int _next_div(struct clk_divider *divider, int div)

{

	div++;



	if (divider->flags & CLK_DIVIDER_POWER_OF_TWO)

		return __roundup_pow_of_two(div);

	if (divider->table)

		return _round_up_table(divider->table, div);



	return div;

}



static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate,

		unsigned long *best_parent_rate)

{
@@ -267,7 +279,7 @@ static int clk_divider_bestdiv(struct clk_hw *hw, unsigned long rate, 
	 */

	maxdiv = min(ULONG_MAX / rate, maxdiv);



	for (i = 1; i <= maxdiv; i++) {

	for (i = 1; i <= maxdiv; i = _next_div(divider, i)) {

		if (!_is_valid_div(divider, i))

			continue;

		if (rate * i == parent_rate_saved) {