linux-kernel - [PATCH] clk: qcom: clk-alpha-pll: Skip reconfiguring the running Lucid Evo

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Message-Id: <20240418-clk-qcom-lucid-evo-skip-configuring-enabled-v1-1-caede5f1c7a3@linaro.org>
Date: Thu, 18 Apr 2024 16:41:32 +0300
From: Abel Vesa <abel.vesa@...aro.org>
To: Bjorn Andersson <andersson@...nel.org>, 
 Michael Turquette <mturquette@...libre.com>, 
 Stephen Boyd <sboyd@...nel.org>, Konrad Dybcio <konrad.dybcio@...aro.org>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: linux-arm-msm@...r.kernel.org, linux-clk@...r.kernel.org, 
 linux-kernel@...r.kernel.org, Abel Vesa <abel.vesa@...aro.org>
Subject: [PATCH] clk: qcom: clk-alpha-pll: Skip reconfiguring the running
 Lucid Evo

The PLL0 is configured by the bootlader and is the parent of the
mdp_clk_src. The Trion implementation of the configure function is
already skipping this step if the PLL is enabled, so lets extend the
same behavior to Lucid Evo variant.

Signed-off-by: Abel Vesa <abel.vesa@...aro.org>
---
 drivers/clk/qcom/clk-alpha-pll.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 8a412ef47e16..4c5aeccff0ef 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -2114,6 +2114,15 @@ void clk_lucid_evo_pll_configure(struct clk_alpha_pll *pll, struct regmap *regma
 {
 	u32 lval = config->l;
 
+	/*
+	 * If the bootloader left the PLL enabled it's likely that there are
+	 * RCGs that will lock up if we disable the PLL below.
+	 */
+	if (trion_pll_is_enabled(pll, regmap)) {
+		pr_debug("Lucid Evo PLL is already enabled, skipping configuration\n");
+		return;
+	}
+
 	lval |= TRION_PLL_CAL_VAL << LUCID_EVO_PLL_CAL_L_VAL_SHIFT;
 	clk_alpha_pll_write_config(regmap, PLL_L_VAL(pll), lval);
 	clk_alpha_pll_write_config(regmap, PLL_ALPHA_VAL(pll), config->alpha);

---
base-commit: 4eab358930711bbeb85bf5ee267d0d42d3394c2c
change-id: 20240418-clk-qcom-lucid-evo-skip-configuring-enabled-711b7e7835b0

Best regards,
-- 
Abel Vesa <abel.vesa@...aro.org>