linux-kernel - [PATCH v3 3/4] clk: amlogic: Add handling for PLL lock failure

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Message-Id: <20251031-optimize_pll_driver-v3-3-92f3b2f36a83@amlogic.com>
Date: Fri, 31 Oct 2025 16:10:10 +0800
From: Chuan Liu via B4 Relay <devnull+chuan.liu.amlogic.com@...nel.org>
To: Neil Armstrong <neil.armstrong@...aro.org>, 
 Jerome Brunet <jbrunet@...libre.com>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Kevin Hilman <khilman@...libre.com>, 
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc: linux-amlogic@...ts.infradead.org, linux-clk@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Chuan Liu <chuan.liu@...ogic.com>
Subject: [PATCH v3 3/4] clk: amlogic: Add handling for PLL lock failure

From: Chuan Liu <chuan.liu@...ogic.com>

If the PLL fails to lock, it should be disabled, This makes the logic
more complete, and also helps save unnecessary power consumption when
the PLL is malfunctioning.

Signed-off-by: Chuan Liu <chuan.liu@...ogic.com>
---
 drivers/clk/meson/clk-pll.c | 41 +++++++++++++++++++++++------------------
 1 file changed, 23 insertions(+), 18 deletions(-)

diff --git a/drivers/clk/meson/clk-pll.c b/drivers/clk/meson/clk-pll.c
index 70c8c7078046..cdb39a723bd0 100644
--- a/drivers/clk/meson/clk-pll.c
+++ b/drivers/clk/meson/clk-pll.c
@@ -353,6 +353,23 @@ static int meson_clk_pcie_pll_enable(struct clk_hw *hw)
 	return -EIO;
 }
 
+static void meson_clk_pll_disable(struct clk_hw *hw)
+{
+	struct clk_regmap *clk = to_clk_regmap(hw);
+	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
+
+	/* Put the pll is in reset */
+	if (MESON_PARM_APPLICABLE(&pll->rst))
+		meson_parm_write(clk->map, &pll->rst, 1);
+
+	/* Disable the pll */
+	meson_parm_write(clk->map, &pll->en, 0);
+
+	/* Disable PLL internal self-adaption current module */
+	if (MESON_PARM_APPLICABLE(&pll->current_en))
+		meson_parm_write(clk->map, &pll->current_en, 0);
+}
+
 static int meson_clk_pll_enable(struct clk_hw *hw)
 {
 	struct clk_regmap *clk = to_clk_regmap(hw);
@@ -399,29 +416,17 @@ static int meson_clk_pll_enable(struct clk_hw *hw)
 		meson_parm_write(clk->map, &pll->l_detect, 0);
 	}
 
-	if (meson_clk_pll_wait_lock(hw))
+	if (meson_clk_pll_wait_lock(hw)) {
+		/* disable PLL when PLL lock failed. */
+		meson_clk_pll_disable(hw);
+		pr_warn("%s: PLL lock failed!\n", clk_hw_get_name(hw));
+
 		return -EIO;
+	}
 
 	return 0;
 }
 
-static void meson_clk_pll_disable(struct clk_hw *hw)
-{
-	struct clk_regmap *clk = to_clk_regmap(hw);
-	struct meson_clk_pll_data *pll = meson_clk_pll_data(clk);
-
-	/* Put the pll is in reset */
-	if (MESON_PARM_APPLICABLE(&pll->rst))
-		meson_parm_write(clk->map, &pll->rst, 1);
-
-	/* Disable the pll */
-	meson_parm_write(clk->map, &pll->en, 0);
-
-	/* Disable PLL internal self-adaption current module */
-	if (MESON_PARM_APPLICABLE(&pll->current_en))
-		meson_parm_write(clk->map, &pll->current_en, 0);
-}
-
 static int meson_clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
 				  unsigned long parent_rate)
 {

-- 
2.42.0