From 4e382f196a4e49944b37ad322e0456c163177b2b Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 5 May 2023 13:25:19 +0200 Subject: [PATCH] clk: lochnagar: Add a determine_rate hook The lochnagar clocks implement a mux with a set_parent hook, but doesn't provide a determine_rate implementation. This is a bit odd, since set_parent() is there to, as its name implies, change the parent of a clock. However, the most likely candidates to trigger that parent change are either the assigned-clock-parents device tree property or a call to clk_set_rate(), with determine_rate() figuring out which parent is the best suited for a given rate. The other trigger would be a call to clk_set_parent(), but it's far less used, and it doesn't look like there's any obvious user for that clock. Since there's no upstream device tree using that driver, it's a bit hard to tell if it uses the assigned-clock properties. The binding and its example uses them though, so it's likely that the author intent was to force the parent through the device tree and prevent any reparenting but through an explicit call to clk_set_parent(). This case is equivalent to setting the determine_rate implementation to clk_hw_determine_rate_no_reparent(). Indeed, if no determine_rate implementation is provided, clk_round_rate() (through clk_core_round_rate_nolock()) will call itself on the parent if CLK_SET_RATE_PARENT is set, and will not change the clock rate otherwise. Cc: Charles Keepax Cc: Richard Fitzgerald Cc: patches@opensource.cirrus.com Tested-by: Charles Keepax Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-17-971d5077e7d2@cerno.tech | Reported-by: kernel test robot : | Reported-by: kernel test robot : Signed-off-by: Stephen Boyd --- drivers/clk/clk-lochnagar.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/clk/clk-lochnagar.c b/drivers/clk/clk-lochnagar.c index 80944bf..db468a6 100644 --- a/drivers/clk/clk-lochnagar.c +++ b/drivers/clk/clk-lochnagar.c @@ -209,6 +209,7 @@ static u8 lochnagar_clk_get_parent(struct clk_hw *hw) static const struct clk_ops lochnagar_clk_ops = { .prepare = lochnagar_clk_prepare, .unprepare = lochnagar_clk_unprepare, + .determine_rate = clk_hw_determine_rate_no_reparent, .set_parent = lochnagar_clk_set_parent, .get_parent = lochnagar_clk_get_parent, }; -- 2.7.4