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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: Maxime Coquelin <maxime.coquelin@st.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
This commit is contained in:
Maxime COQUELIN 2014-01-29 17:24:08 +01:00 committed by Mike Turquette
parent 774b514390
commit 0e2de78ecd
1 changed files with 13 additions and 1 deletions
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14
drivers/clk/clk-divider.c
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@ -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) {