[PATCH 2/4] clk: qcom: clk-alpha-pll: Skip Zonda PLL configuration if already enabled

[Kathiravan Thirumoorthy]

On IPQ9650, the bootloader configures and enables the APSS Zonda PLL
that provide the clocks for the A55 CPU cores and L3 interconnect. When
the APSS clock driver probes, it attempts to reconfigure the already
running PLLs. As part of the reconfiguration sequence, the PLL output is
disabled and the PLL is placed into standby before being re-enabled.
Since the CPUs are actively clocked from these PLLs, removing the clock
during this window causes the system to hang.

Avoid reconfiguring PLLs that are already enabled and return early,
similar to clk_trion_pll_configure().

Signed-off-by: Kathiravan Thirumoorthy <kathiravan.thirumoorthy@xxxxxxxxxxxxxxxx>
---
 drivers/clk/qcom/clk-alpha-pll.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/clk/qcom/clk-alpha-pll.c b/drivers/clk/qcom/clk-alpha-pll.c
index 60173b076cc5..3641b2da92cd 100644
--- a/drivers/clk/qcom/clk-alpha-pll.c
+++ b/drivers/clk/qcom/clk-alpha-pll.c
@@ -2162,6 +2162,10 @@ EXPORT_SYMBOL_GPL(clk_alpha_pll_postdiv_lucid_5lpe_ops);
 void clk_zonda_pll_configure(struct clk_alpha_pll *pll, struct regmap *regmap,
 			     const struct alpha_pll_config *config)
 {
+	/* Check if PLL is already enabled */
+	if (trion_pll_is_enabled(pll, regmap))
+		return;
+
 	clk_alpha_pll_write_config(regmap, PLL_L_VAL(pll), config->l);
 	clk_alpha_pll_write_config(regmap, PLL_ALPHA_VAL(pll), config->alpha);
 	clk_alpha_pll_write_config(regmap, PLL_CONFIG_CTL(pll), config->config_ctl_val);

-- 
2.34.1