Re: [PATCH v8 1/4] irqchip: gic: Support hierarchy irq domain.

From: Marc Zyngier
Date: Tue Dec 02 2014 - 09:12:24 EST

On 02/12/14 13:55, Geert Uytterhoeven wrote:
> Hi Marc,
> On Tue, Dec 2, 2014 at 2:37 PM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
>> On 02/12/14 13:27, Geert Uytterhoeven wrote:
>>> On Tue, Nov 25, 2014 at 9:04 AM, Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx> wrote:
>>>> Add support to use gic as a parent for stacked irq domain.
>>>> Signed-off-by: Yingjoe Chen <yingjoe.chen@xxxxxxxxxxxx>
>>> This change (which is now in -next as commit 9a1091ef0017c40a) breaks
>>> booting on r8a7740/armadillo-legacy.
>>> It hangs because the timers cannot get their interrupts:
>>> console [tty0] enabled
>>> sh-tmu.0: ch0: used for clock events
>>> sh-tmu.0: ch0: used for periodic clock events
>>> sh-tmu.0: ch0: failed to request irq 230
>>> sh-tmu.0: ch1: used as clock source
>>> sh-cmt-48.1: ch0: failed to request irq 90
>>> sh-cmt-48.1: ch0: registration failed
>>> earlytimer: unable to probe sh-cmt-48 early.
>>> Calibrating delay loop...
>> Grmbl... Are you, by any (lack of) chance, using a setup where the GIC
>> is probed via DT, but the timers have their IRQs hardcoded?
> Yes, the GIC is declared in arch/arm/boot/dts/r8a7740.dtsi:
> gic: interrupt-controller@c2800000 {
> compatible = "arm,cortex-a9-gic";
> #interrupt-cells = <3>;
> interrupt-controller;
> reg = <0xc2800000 0x1000>,
> <0xc2000000 0x1000>;
> };
> The timers come from legacy C board code in
> arch/arm/mach-shmobile/setup-r8a7740.c:
> /* CMT */
> static struct sh_timer_config cmt1_platform_data = {
> .channels_mask = 0x3f,
> };
> static struct resource cmt1_resources[] = {
> DEFINE_RES_MEM(0xe6138000, 0x170),
> DEFINE_RES_IRQ(gic_spi(58)),
> };

Yup. This gic_spi() macro is completely doomed, as it computes a
hardware interrupt where the kernel expects a virtual one. The only way
to fix this is to init the GIC outside of DT, so that we stick to a
legacy irqdomain. You can still use information from DT, but you can't
rely on irqchip_init() to produce something that a legacy platform can use.

> The corresponding r8a7740/armadillo-multiplatform works fine.

OK, that's indeed the expected result.

> Still, I'm wondering why sh73a0/kzm9g-legacy is not impacted by this
> change...

I'm a bit lost looking at the shmobile code. But I agree, kzm9g should
die a painful death, as it has the same level of breakage as armadillo.

Jazz is not dead. It just smells funny...
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at