linux-kernel - [PATCH 5.4 437/453] clk: ingenic: Fix divider calculation with div tables

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Date:   Mon, 28 Dec 2020 13:51:13 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Paul Cercueil <paul@...pouillou.net>,
        Stephen Boyd <sboyd@...nel.org>
Subject: [PATCH 5.4 437/453] clk: ingenic: Fix divider calculation with div tables

From: Paul Cercueil <paul@...pouillou.net>

commit 11a163f2c7d6a9f27ce144cd7e367a81c851621a upstream.

The previous code assumed that a higher hardware value always resulted
in a bigger divider, which is correct for the regular clocks, but is
an invalid assumption when a divider table is provided for the clock.

Perfect example of this is the PLL0_HALF clock, which applies a /2
divider with the hardware value 0, and a /1 divider otherwise.

Fixes: a9fa2893fcc6 ("clk: ingenic: Add support for divider tables")
Cc: <stable@...r.kernel.org> # 5.2
Signed-off-by: Paul Cercueil <paul@...pouillou.net>
Link: https://lore.kernel.org/r/20201212135733.38050-1-paul@crapouillou.net
Signed-off-by: Stephen Boyd <sboyd@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/clk/ingenic/cgu.c |   14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

--- a/drivers/clk/ingenic/cgu.c
+++ b/drivers/clk/ingenic/cgu.c
@@ -393,15 +393,21 @@ static unsigned int
 ingenic_clk_calc_hw_div(const struct ingenic_cgu_clk_info *clk_info,
 			unsigned int div)
 {
-	unsigned int i;
+	unsigned int i, best_i = 0, best = (unsigned int)-1;
 
 	for (i = 0; i < (1 << clk_info->div.bits)
 				&& clk_info->div.div_table[i]; i++) {
-		if (clk_info->div.div_table[i] >= div)
-			return i;
+		if (clk_info->div.div_table[i] >= div &&
+		    clk_info->div.div_table[i] < best) {
+			best = clk_info->div.div_table[i];
+			best_i = i;
+
+			if (div == best)
+				break;
+		}
 	}
 
-	return i - 1;
+	return best_i;
 }
 
 static unsigned