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From:   Maxime Ripard <maxime@cerno.tech>
Date:   Tue, 04 Apr 2023 12:11:34 +0200
Subject: [PATCH v3 44/65] clk: actions: composite: div: Switch to
 determine_rate
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To:     Michael Turquette <mturquette@baylibre.com>,
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Cc:     linux-clk@vger.kernel.org, linux-kernel@vger.kernel.org,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-actions@lists.infradead.org, patches@opensource.cirrus.com,
        linux-stm32@st-md-mailman.stormreply.com,
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        Maxime Ripard <maxime@cerno.tech>
Precedence: bulk

The Actions composite divider 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.

Signed-off-by: Maxime Ripard <maxime@cerno.tech>
---
 drivers/clk/actions/owl-composite.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/actions/owl-composite.c b/drivers/clk/actions/owl-composite.c
index 4c844a5613e4..d66b268563d0 100644
--- a/drivers/clk/actions/owl-composite.c
+++ b/drivers/clk/actions/owl-composite.c
@@ -53,13 +53,19 @@ static int owl_comp_is_enabled(struct clk_hw *hw)
 	return owl_gate_clk_is_enabled(common, &comp->gate_hw);
 }
 
-static long owl_comp_div_round_rate(struct clk_hw *hw, unsigned long rate,
-				unsigned long *parent_rate)
+static int owl_comp_div_determine_rate(struct clk_hw *hw,
+				       struct clk_rate_request *req)
 {
 	struct owl_composite *comp = hw_to_owl_comp(hw);
+	long rate;
 
-	return owl_divider_helper_round_rate(&comp->common, &comp->rate.div_hw,
-					rate, parent_rate);
+	rate = owl_divider_helper_round_rate(&comp->common, &comp->rate.div_hw,
+					     req->rate, &req->best_parent_rate);
+	if (rate < 0)
+		return rate;
+
+	req->rate = rate;
+	return 0;
 }
 
 static unsigned long owl_comp_div_recalc_rate(struct clk_hw *hw,
@@ -152,7 +158,7 @@ const struct clk_ops owl_comp_div_ops = {
 	.is_enabled	= owl_comp_is_enabled,
 
 	/* div_ops */
-	.round_rate	= owl_comp_div_round_rate,
+	.determine_rate	= owl_comp_div_determine_rate,
 	.recalc_rate	= owl_comp_div_recalc_rate,
 	.set_rate	= owl_comp_div_set_rate,
 };

-- 
2.39.2