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Subject[PATCH 3/3] clk: divider: Optimize clk_divider_bestdiv loop
Date
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>
---
drivers/clk/clk-divider.c | 14 +++++++++++++-
1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c
index 1eaa5d8..4aabf4f 100644
--- a/drivers/clk/clk-divider.c
+++ b/drivers/clk/clk-divider.c
@@ -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) {
--
1.7.9.5


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