[PATCH v3] clk: at91: optimize clk_round_rate() for AUDIO_PLL
From: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Date: 2018-12-18 11:20:52
Also in:
linux-clk
Subsystem:
common clk framework, the rest · Maintainers:
Michael Turquette, Stephen Boyd, Linus Torvalds
Stop the search for parent rate when exact match is found. This makes for 3 clk_round_rate() calls instead of 64 of them on SAMA5D2-based board when searching for 12.288MHz clock. Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl> --- v2: rebased on v4.20-rc7 v3: formatting and commit description changes --- drivers/clk/at91/clk-audio-pll.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/clk/at91/clk-audio-pll.c b/drivers/clk/at91/clk-audio-pll.c
index 36d77146a3bd..3cc4a82f4e9f 100644
--- a/drivers/clk/at91/clk-audio-pll.c
+++ b/drivers/clk/at91/clk-audio-pll.c@@ -340,7 +340,12 @@ static long clk_audio_pll_pmc_round_rate(struct clk_hw *hw, unsigned long rate, pr_debug("A PLL/PMC: %s, rate = %lu (parent_rate = %lu)\n", __func__, rate, *parent_rate); - for (div = 1; div <= AUDIO_PLL_QDPMC_MAX; div++) { + if (!rate) + return 0; + + best_parent_rate = clk_round_rate(pclk->clk, 1); + div = max(best_parent_rate / rate, 1UL); + for (; div <= AUDIO_PLL_QDPMC_MAX; div++) { best_parent_rate = clk_round_rate(pclk->clk, rate * div); tmp_rate = best_parent_rate / div; tmp_diff = abs(rate - tmp_rate);
@@ -350,6 +355,8 @@ static long clk_audio_pll_pmc_round_rate(struct clk_hw *hw, unsigned long rate, best_rate = tmp_rate; best_diff = tmp_diff; tmp_qd = div; + if (!best_diff) + break; /* got exact match */ } }
--
2.19.2
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