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

[Marc Zyngier <maz@kernel.org>]

Hi Sander,

On Thu, 18 Nov 2021 15:56:06 +0000,
Sander Vanheule <sander@svanheule.net> wrote:
> 
> 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.

Thanks for the heads up.

> 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.

OK, back to square one, we need to debug this one.

[...]

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

[...]

>
> 		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 */
> 		};

Something looks pretty odd. With 5.15, this interrupt-map would be
completely ignored. With 5.16-rc1, we should actually honour it.

/me digs...

Gah, I see. This driver has its own interrupt-map parser and invents
something out of thin air. I will bang my own head on the wall for
having merged this horror.

Can you try applying the patch below and rename the interrupt-map
property in your DT to "silly-interrupt-map" and let me know if that
helps?

That's of course not the right fix, but that's just to confirm the
extent of the damage...

	M.

diff --git a/drivers/irqchip/irq-realtek-rtl.c b/drivers/irqchip/irq-realtek-rtl.c
index fd9f275592d2..3641cd2b1a2c 100644
--- a/drivers/irqchip/irq-realtek-rtl.c
+++ b/drivers/irqchip/irq-realtek-rtl.c
@@ -114,7 +114,7 @@ static int __init map_interrupts(struct device_node *node, struct irq_domain *do
 	if (ret || tmp)
 		return -EINVAL;
 
-	imap = of_get_property(node, "interrupt-map", &imaplen);
+	imap = of_get_property(node, "silly-interrupt-map", &imaplen);
 	if (!imap || imaplen % 3)
 		return -EINVAL;
 

-- 
Without deviation from the norm, progress is not possible.