realtek,rtl-intc IRQ mapping broken on 5.16-rc1

[Sander Vanheule <sander@svanheule.net>]

Hi everyone,

On 5.16-rc1, the realtek,rtl-intc interrupt controller driver for Realtek RTL8380 SoCs
(and related) appears broken. When booting, I don't get a tty on the serial port, although
serial output works.

The watchdog (currently under review) also cannot acquire the required phase1 interrupt,
and produces the following output:
[    1.968228] realtek-otto-watchdog 18003150.watchdog: error -EINVAL: Failed to get IRQ 4
for phase1
[    1.978404] realtek-otto-watchdog: probe of 18003150.watchdog failed with error -22

A bisects points to commit 041284181226 ("of/irq: Allow matching of an interrupt-map local
to an interrupt controller"). Reverting this above commit and follow-up commit
10a20b34d735 ("of/irq: Don't ignore interrupt-controller when interrupt-map failed")
restores the functionality from v5.15.

Below you can find the DTS that I used to reproduce this on my Zyxel GS1900-8.


Best,
Sander

---
// SPDX-License-Identifier: GPL-2.0-or-later
/dts-v1/;

/ {
	#address-cells = <1>;
	#size-cells = <1>;

	compatible = "zyxel,gs1900-8", "realtek,rtl83xx-soc";
	model = "ZyXEL GS1900-8";

	aliases {
		serial0 = &serial0;
	};

	baseclk: baseclk {
		compatible = "fixed-clock";
		#clock-cells = <0>;
		clock-frequency = <500000000>;
	};

	chosen {
		stdout-path = "serial0";
		bootargs = "earlycon console=ttyS0,115200";
	};

	cpuintc: cpuintc {
		compatible = "mti,cpu-interrupt-controller";
		#address-cells = <0>;
		#interrupt-cells = <1>;
		interrupt-controller;
	};

	cpus {
		#address-cells = <1>;
		#size-cells = <0>;

		cpu@0 {
			compatible = "mips,mips4KEc";
			reg = <0>;
			clocks = <&baseclk>;
			clock-names = "cpu";
		};
	};

	lx_clk: lx_clk {
		compatible = "fixed-clock";
		#clock-cells = <0>;
		clock-frequency = <200000000>;
	};

	memory@0 {
		device_type = "memory";
		reg = <0x0 0x8000000>;
	};

	soc: soc@18000000 {
		compatible = "simple-bus";
		#address-cells = <1>;
		#size-cells = <1>;
		ranges = <0x0 0x18000000 0x10000>;

		serial0: serial@2000 {
			compatible = "ns16550a";
			reg = <0x2000 0x100>;

			clocks = <&lx_clk>;

			interrupt-parent = <&intc>;
			interrupts = <31>;

			reg-io-width = <1>;
			reg-shift = <2>;
			fifo-size = <1>;
			no-loopback-test;
		};

		intc: interrupt-controller@3000 {
			compatible = "realtek,rtl-intc";
			reg = <0x3000 0x20>;
			interrupt-controller;
			#interrupt-cells = <1>;

			#address-cells = <0>;
			interrupt-map =
				<31 &cpuintc 2>, /* UART0 */
				<20 &cpuintc 3>, /* SWCORE */
				<19 &cpuintc 4>, /* WDT IP1 */
				<18 &cpuintc 5>; /* WDT IP2 */
		};

		watchdog@3150 {
			compatible = "realtek,rtl8380-wdt";
			reg = <0x3150 0xc>;

			realtek,reset-mode = "soc";

			clocks = <&lx_clk>;
			timeout-sec = <20>;

			interrupt-parent = <&intc>;
			interrupt-names = "phase1", "phase2";
			interrupts = <19>, <18>;
		};
	};
};