From 15d3f365abff5823998ea4976ee0cbce12047637 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 5 May 2023 13:26:00 +0200 Subject: [PATCH] clk: imx: scu: Switch to determine_rate The iMX SCU clocks 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 candidate to trigger that parent change is 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. So, the set_parent hook is effectively unused, possibly because of an oversight. However, it could also be an explicit decision by the original author to avoid any reparenting but through an explicit call to clk_set_parent(). The driver does implement round_rate() though, which means that we can change the rate of the clock, but we will never get to change the parent. However, It's hard to tell whether it's been done on purpose or not. Since we'll start mandating a determine_rate() implementation, let's convert the round_rate() implementation to a determine_rate(), which will also make the current behavior explicit. The round_rate() implementation being shared with other clocks, it's not removed. And if it was an oversight, the clock behaviour can be adjusted later on. Cc: Abel Vesa Cc: Fabio Estevam Cc: Peng Fan Cc: Sascha Hauer Cc: Shawn Guo Cc: linux-arm-kernel@lists.infradead.org Cc: NXP Linux Team Cc: Pengutronix Kernel Team Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-58-971d5077e7d2@cerno.tech Signed-off-by: Stephen Boyd --- drivers/clk/imx/clk-scu.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/clk/imx/clk-scu.c b/drivers/clk/imx/clk-scu.c index 417f893f8895..725b7b3edb63 100644 --- a/drivers/clk/imx/clk-scu.c +++ b/drivers/clk/imx/clk-scu.c @@ -250,6 +250,23 @@ static unsigned long clk_scu_recalc_rate(struct clk_hw *hw, return le32_to_cpu(msg.data.resp.rate); } +/* + * clk_scu_determine_rate - Returns the closest rate for a SCU clock + * @hw: clock to round rate for + * @req: clock rate request + * + * Returns 0 on success, a negative error on failure + */ +static int clk_scu_determine_rate(struct clk_hw *hw, + struct clk_rate_request *req) +{ + /* + * Assume we support all the requested rate and let the SCU firmware + * to handle the left work + */ + return 0; +} + /* * clk_scu_round_rate - Round clock rate for a SCU clock * @hw: clock to round rate for @@ -425,7 +442,7 @@ static void clk_scu_unprepare(struct clk_hw *hw) static const struct clk_ops clk_scu_ops = { .recalc_rate = clk_scu_recalc_rate, - .round_rate = clk_scu_round_rate, + .determine_rate = clk_scu_determine_rate, .set_rate = clk_scu_set_rate, .get_parent = clk_scu_get_parent, .set_parent = clk_scu_set_parent,