linux-kernel - [PATCH RFC 2/4] clk: reset new

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Message-Id: <20231002-ccf-set-multiple-v1-2-2df5e9eb3738@skidata.com>
Date:   Mon, 02 Oct 2023 11:23:33 +0200
From:   Benjamin Bara <bbara93@...il.com>
To:     Maxime Ripard <mripard@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>
Cc:     Frank Oltmanns <frank@...manns.dev>,
        Adam Ford <aford173@...il.com>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Benjamin Bara <benjamin.bara@...data.com>
Subject: [PATCH RFC 2/4] clk: reset new_rates for next run

From: Benjamin Bara <benjamin.bara@...data.com>

During clk_set_rate(), new_rates are calculated for all clocks that are
part of the changed clock subtree. These values are temporary and only
valid during the current call. Therefore, reset them to prepare a clean
state for the next call.

Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
---
 drivers/clk/clk.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index 82f954121e4d..5f183cba300c 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -2163,6 +2163,17 @@ static void clk_calc_subtree(struct clk_core *core, unsigned long new_rate,
 	}
 }
 
+static void clk_reset_temp_rates(struct clk_core *core)
+{
+	struct clk_core *child;
+
+	core->new_rate = CLK_RATE_UNSET;
+
+	hlist_for_each_entry(child, &core->children, child_node) {
+		clk_reset_temp_rates(child);
+	}
+}
+
 /*
  * calculate the new rates returning the topmost clock that has to be
  * changed.
@@ -2244,7 +2255,9 @@ static struct clk_core *clk_calc_new_rates(struct clk_core *core,
 		top = clk_calc_new_rates(parent, best_parent_rate);
 
 out:
-	clk_calc_subtree(core, new_rate, parent, p_index);
+	/* only set new_rates if we found a valid change path */
+	if (top)
+		clk_calc_subtree(core, new_rate, parent, p_index);
 
 	return top;
 }
@@ -2347,6 +2360,7 @@ static void clk_change_rate(struct clk_core *core)
 
 	trace_clk_set_rate_complete(core, core->new_rate);
 
+	core->new_rate = CLK_RATE_UNSET;
 	core->rate = clk_recalc(core, best_parent_rate);
 
 	if (core->flags & CLK_SET_RATE_UNGATE) {
@@ -2361,7 +2375,7 @@ static void clk_change_rate(struct clk_core *core)
 		__clk_notify(core, POST_RATE_CHANGE, old_rate, core->rate);
 
 	if (core->flags & CLK_RECALC_NEW_RATES)
-		(void)clk_calc_new_rates(core, core->new_rate);
+		(void)clk_calc_new_rates(core, core->rate);
 
 	/*
 	 * Use safe iteration, as change_rate can actually swap parents
@@ -2437,8 +2451,10 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
 		return -EINVAL;
 
 	ret = clk_pm_runtime_get(core);
-	if (ret)
+	if (ret) {
+		clk_reset_temp_rates(top);
 		return ret;
+	}
 
 	/* notify that we are about to change rates */
 	fail_clk = clk_propagate_rate_change(top, PRE_RATE_CHANGE);
@@ -2454,6 +2470,8 @@ static int clk_core_set_rate_nolock(struct clk_core *core,
 	clk_change_rate(top);
 
 err:
+	clk_reset_temp_rates(top);
+
 	clk_pm_runtime_put(core);
 
 	return ret;
@@ -3900,6 +3918,7 @@ static int __clk_core_init(struct clk_core *core)
 		rate = 0;
 	core->rate = rate;
 	core->req_rate = CLK_RATE_UNSET;
+	core->new_rate = CLK_RATE_UNSET;
 
 	/*
 	 * Enable CLK_IS_CRITICAL clocks so newly added critical clocks

-- 
2.34.1