From mboxrd@z Thu Jan 1 00:00:00 1970 From: maxime.coquelin@st.com (Maxime COQUELIN) Date: Wed, 29 Jan 2014 17:24:08 +0100 Subject: [PATCH 3/3] clk: divider: Optimize clk_divider_bestdiv loop In-Reply-To: <1391012648-12481-1-git-send-email-maxime.coquelin@st.com> References: <1391012648-12481-1-git-send-email-maxime.coquelin@st.com> Message-ID: <1391012648-12481-4-git-send-email-maxime.coquelin@st.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 --- 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