From mboxrd@z Thu Jan 1 00:00:00 1970 From: moinejf@free.fr (Jean-Francois Moine) Date: Thu, 10 Mar 2016 08:15:02 +0100 Subject: [PATCH] clk: sunxi: Accept a greater rate when setting a parent clock Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org The best rate of a clock may be a bit greater than the requested one. In such a case, the rate setting from a child clock was rejected. Signed-off-by: Jean-Francois Moine --- I don't know exactly why the rate constraint existed nor what can be the impact of setting the rate of other clocks. I had the problem when setting the PLL2 clock of the H3 (patch to come). It has 4 outputs, so, it is composed of a base clock and 4 children clocks pll2, pll2x2, pll2x4 and pll2x8 with a fixed factor (/4, /2, 1 and *2). The pll2 clock rate may be only 24576000 (for the audio family 48000Hz) or 22579200 (for the audio family 44100Hz). Setting 24576000 asks for mul=86 and div=21,4 giving 24571428 as the best rate, i.e. a bit slower than requested: good. Setting 22579200 asks for mul=64 and div=17,4 giving 22588235, i.e. a bit greater: then, the rate setting was rejected (no parent clock), preventing audio streaming at 44100Hz. --- drivers/clk/sunxi/clk-factors.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/clk/sunxi/clk-factors.c b/drivers/clk/sunxi/clk-factors.c index 59428db..d0774c2 100644 --- a/drivers/clk/sunxi/clk-factors.c +++ b/drivers/clk/sunxi/clk-factors.c @@ -86,7 +86,7 @@ static int clk_factors_determine_rate(struct clk_hw *hw, int i, num_parents; unsigned long parent_rate, best = 0, child_rate, best_child_rate = 0; - /* find the parent that can help provide the fastest rate <= rate */ + /* find the parent that can help provide the fastest rate */ num_parents = clk_hw_get_num_parents(hw); for (i = 0; i < num_parents; i++) { parent = clk_hw_get_parent_by_index(hw, i); @@ -100,7 +100,7 @@ static int clk_factors_determine_rate(struct clk_hw *hw, child_rate = clk_factors_round_rate(hw, req->rate, &parent_rate); - if (child_rate <= req->rate && child_rate > best_child_rate) { + if (child_rate > best_child_rate) { best_parent = parent; best = parent_rate; best_child_rate = child_rate; -- 2.7.2