[PATCH 1/4] riscv: dts: spacemit: k3-com260: keep dldo4 enabled

[Jennifer Berringer <jberring@redhat.com>]

From: James Morris <jmorris@namei.org>

dldo4 on the P1 PMIC is marked regulator-boot-on, but has no consumer
described in the device tree. The regulator core can therefore disable
the firmware-enabled rail during unused-regulator cleanup.

Enabling pcie4_rc on a K3 CoM260 Dev Kit without this change while the
board's included RTL8852BE module is connected to the M.2 E-key slot
results in CPU hard-lock, as seen in kernel log:

[   32.521536] dldo4: disabling
[   48.125823] watchdog: CPU3: Watchdog detected hard LOCKUP on cpu 4
[   64.125829] watchdog: BUG: soft lockup - CPU#1 stuck for 26s!
[   64.125926] Hardware name: SpacemiT K3 CoM260 IFX (DT)
[   64.125928] epc : smp_call_function_many_cond+0x158/0x740
[   64.125938]  ra : smp_call_function_many_cond+0x11a/0x740

GitHub Copilot assisted with diagnosis and build and test automation, and
changelog drafting.

Fixes: cfe5c91cb73c ("riscv: dts: spacemit: k3: Initial support for CoM260-IFX board")
Assisted-by: GitHub-Copilot:gpt-sol-5.6
Signed-off-by: James Morris <jmorris@namei.org> (Microsoft)
Signed-off-by: Jennifer Berringer <jberring@redhat.com>
---
 arch/riscv/boot/dts/spacemit/k3-com260.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/riscv/boot/dts/spacemit/k3-com260.dtsi b/arch/riscv/boot/dts/spacemit/k3-com260.dtsi
index 92dea86397798..054bfff7413a3 100644
--- a/arch/riscv/boot/dts/spacemit/k3-com260.dtsi
+++ b/arch/riscv/boot/dts/spacemit/k3-com260.dtsi
@@ -187,6 +187,7 @@ dldo3: dldo3 {
 			dldo4: dldo4 {
 				regulator-min-microvolt = <1800000>;
 				regulator-max-microvolt = <1800000>;
+				regulator-always-on;
 				regulator-boot-on;
 			};
 
-- 
2.55.0