From 6a25bd4d1d00baaf32a0da76631db47adeea7b56 Mon Sep 17 00:00:00 2001 From: Maxime Ripard Date: Fri, 5 May 2023 13:25:51 +0200 Subject: [PATCH] clk: at91: smd: Switch to determine_rate The Atmel SAM9x5 SMD 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. And if it was an oversight, the clock behaviour can be adjusted later on. Cc: Alexandre Belloni Cc: Claudiu Beznea Cc: Nicolas Ferre Cc: linux-arm-kernel@lists.infradead.org Signed-off-by: Maxime Ripard Link: https://lore.kernel.org/r/20221018-clk-range-checks-fixes-v4-49-971d5077e7d2@cerno.tech Signed-off-by: Stephen Boyd --- drivers/clk/at91/clk-smd.c | 29 +++++++++++++++++------------ 1 file changed, 17 insertions(+), 12 deletions(-) diff --git a/drivers/clk/at91/clk-smd.c b/drivers/clk/at91/clk-smd.c index 1603784..09c649c 100644 --- a/drivers/clk/at91/clk-smd.c +++ b/drivers/clk/at91/clk-smd.c @@ -36,26 +36,31 @@ static unsigned long at91sam9x5_clk_smd_recalc_rate(struct clk_hw *hw, return parent_rate / (smddiv + 1); } -static long at91sam9x5_clk_smd_round_rate(struct clk_hw *hw, unsigned long rate, - unsigned long *parent_rate) +static int at91sam9x5_clk_smd_determine_rate(struct clk_hw *hw, + struct clk_rate_request *req) { unsigned long div; unsigned long bestrate; unsigned long tmp; - if (rate >= *parent_rate) - return *parent_rate; + if (req->rate >= req->best_parent_rate) { + req->rate = req->best_parent_rate; + return 0; + } - div = *parent_rate / rate; - if (div > SMD_MAX_DIV) - return *parent_rate / (SMD_MAX_DIV + 1); + div = req->best_parent_rate / req->rate; + if (div > SMD_MAX_DIV) { + req->rate = req->best_parent_rate / (SMD_MAX_DIV + 1); + return 0; + } - bestrate = *parent_rate / div; - tmp = *parent_rate / (div + 1); - if (bestrate - rate > rate - tmp) + bestrate = req->best_parent_rate / div; + tmp = req->best_parent_rate / (div + 1); + if (bestrate - req->rate > req->rate - tmp) bestrate = tmp; - return bestrate; + req->rate = bestrate; + return 0; } static int at91sam9x5_clk_smd_set_parent(struct clk_hw *hw, u8 index) @@ -98,7 +103,7 @@ static int at91sam9x5_clk_smd_set_rate(struct clk_hw *hw, unsigned long rate, static const struct clk_ops at91sam9x5_smd_ops = { .recalc_rate = at91sam9x5_clk_smd_recalc_rate, - .round_rate = at91sam9x5_clk_smd_round_rate, + .determine_rate = at91sam9x5_clk_smd_determine_rate, .get_parent = at91sam9x5_clk_smd_get_parent, .set_parent = at91sam9x5_clk_smd_set_parent, .set_rate = at91sam9x5_clk_smd_set_rate, -- 2.7.4