Messages in this thread Patch in this message | | | From | Yang Xiwen via B4 Relay <> | Date | Thu, 15 Feb 2024 23:09:11 +0800 | Subject | [PATCH] clk: set initial best mux parent to current parent when determining rate |
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From: Yang Xiwen <forbidden405@outlook.com>
Originally, the initial clock rate is hardcoded to 0, this can lead to some problem when setting a very small rate with CLK_MUX_ROUND_NEAREST.
For example, if the lowest possible rate privided by the mux is 1000Hz, setting a rate below 500Hz will fail, because no clock can provide a better rate than the non-existant 0. But it should succeed with 1000Hz being set.
Setting the initial best parent to current parent could solve this bug very well.
Signed-off-by: Yang Xiwen <forbidden405@outlook.com> --- This is actually a v2 of [1], but seems too simple to have a unittest. It's tested in a mmc host driver.
[1]: https://lore.kernel.org/linux-clk/20230421-clk-v3-1-9ff79e7e7fed@outlook.com/ --- drivers/clk/clk.c | 4 ++++ 1 file changed, 4 insertions(+)
diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c index 2253c154a824..d98cebd7ff03 100644 --- a/drivers/clk/clk.c +++ b/drivers/clk/clk.c @@ -649,6 +649,10 @@ int clk_mux_determine_rate_flags(struct clk_hw *hw, /* find the parent that can provide the fastest rate <= rate */ num_parents = core->num_parents; + if (core->parent) { + best_parent = core->parent; + best = clk_core_get_rate_nolock(best_parent); + } for (i = 0; i < num_parents; i++) { unsigned long parent_rate; --- base-commit: 8d3dea210042f54b952b481838c1e7dfc4ec751d change-id: 20240215-mux-6db8b3714590 Best regards, -- Yang Xiwen <forbidden405@outlook.com>
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