[PATCH] soc: qcom: geni-se: don't fail ACPI probe on a missing SE clock

[Rahul Pon <theflyingrahul@gmail.com>]

geni_se_resources_init() tolerates a missing "se" clock for devices with an
ACPI companion, whose firmware manages the serial-engine clocks, but then
calls devm_pm_opp_set_clkname() for that same clock unconditionally. It
fails, so ACPI GENI controllers such as the I2C IDs QCOM0220 and QCOM0411
no longer probe. Before the OPP call, the error pointer left in se->clk
would also have reached clk_get_rate().

Treat an absent ACPI SE clock as firmware-owned: store NULL, which the
clock API accepts as a no-op (clk_get_rate() returns 0, so the I2C driver
selects its 19.2 MHz timing table), and skip the OPP clock name. DT
behaviour is unchanged.

Found by code review while bringing up an ACPI-booted Snapdragon X2
laptop; compile-tested with arm64 defconfig plus ACPI and W=1.

Fixes: 5b8a39dcf909 ("soc: qcom: geni-se: Introduce helper API for resource initialization")
Assisted-by: LLM
Signed-off-by: Rahul Pon <theflyingrahul@gmail.com>
---
 drivers/soc/qcom/qcom-geni-se.c | 22 ++++++++++++++++------
 1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/drivers/soc/qcom/qcom-geni-se.c b/drivers/soc/qcom/qcom-geni-se.c
index 873bfbd6b2..5d4b26e95e 100644
--- a/drivers/soc/qcom/qcom-geni-se.c
+++ b/drivers/soc/qcom/qcom-geni-se.c
@@ -1203,13 +1203,23 @@ int geni_se_resources_init(struct geni_se *se)
 				     "Failed to get optional core clk\n");
 
 	se->clk = devm_clk_get(se->dev, "se");
-	if (IS_ERR(se->clk) && !has_acpi_companion(se->dev))
-		return dev_err_probe(se->dev, PTR_ERR(se->clk),
-				     "Failed to get SE clk\n");
+	if (IS_ERR(se->clk)) {
+		if (!has_acpi_companion(se->dev))
+			return dev_err_probe(se->dev, PTR_ERR(se->clk),
+					     "Failed to get SE clk\n");
+		/*
+		 * ACPI firmware owns the SE clock and its rate. The clock API
+		 * treats NULL as a no-op, whereas an error pointer must not
+		 * reach clk_get_rate() or the OPP core.
+		 */
+		se->clk = NULL;
+	}
 
-	ret = devm_pm_opp_set_clkname(se->dev, "se");
-	if (ret)
-		return ret;
+	if (se->clk) {
+		ret = devm_pm_opp_set_clkname(se->dev, "se");
+		if (ret)
+			return ret;
+	}
 
 	ret = devm_pm_opp_of_add_table(se->dev);
 	if (ret && ret != -ENODEV)

base-commit: 551c722f40809618230001baccf219193e22fc5a
-- 
2.53.0