From 5ce89dcc68071899070ba0c381b3eec2d09b2d5d Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 5 May 2023 13:25:22 +0200 Subject: [PATCH] clk: stm32f4: mux: Add a determine_rate hook The STM32F4 mux clock implements 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. However, the upstream device trees seem to use assigned-clock-parents on that clock to force the parent at boot time, 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 would be 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: Alexandre Torgue Cc: Maxime Coquelin Cc: linux-arm-kernel@lists.infradead.org Cc: linux-stm32@st-md-mailman.stormreply.com Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-20-971d5077e7d2@cerno.tech Signed-off-by: Stephen Boyd --- drivers/clk/clk-stm32f4.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/clk/clk-stm32f4.c b/drivers/clk/clk-stm32f4.c index 473dfe6..07c13eb 100644 --- a/drivers/clk/clk-stm32f4.c +++ b/drivers/clk/clk-stm32f4.c @@ -1045,6 +1045,7 @@ static int cclk_mux_set_parent(struct clk_hw *hw, u8 index) } static const struct clk_ops cclk_mux_ops = { + .determine_rate = clk_hw_determine_rate_no_reparent, .get_parent = cclk_mux_get_parent, .set_parent = cclk_mux_set_parent, }; -- 2.7.4