Re: [PATCH] ARM: shmobile: r8a73a4: Move pfc node to work around probe ordering bug
From: Geert Uytterhoeven
Date: Mon Feb 09 2015 - 12:14:31 EST
On Mon, Feb 9, 2015 at 5:24 PM, Tony Lindgren <tony@xxxxxxxxxxx> wrote:
> * Geert Uytterhoeven <geert+renesas@xxxxxxxxx> [150206 12:26]:
>> Currently the pin function controller (which is also a GPIO controller)
>> is instantiated before the interrupt controllers due to the order in the
>> DTS. At that time, the irq domains for the interrupt controllers
>> referenced by its interrupts-extended property cannot be found yet:
>> irq: no irq domain found for /interrupt-controller@e61c0000 !
>> Nevertheless, the core OF probing code ignores this failure, besides a
>> debug message that's not normally printed:
>> not all legacy IRQ resources mapped for pfc
>> and continues initialization of the device. Then, the sh-pfc driver
>> cannot find any IRQ resources, and thinks no interrupts are available,
>> causing gpio-keys to fail later:
>> gpio-keys keyboard: Unable to claim irq 0; error -22
>> gpio-keys: probe of keyboard failed with error -22
>> Move the pin function controller node after the interrupt controller
>> nodes it references to work around the bug in the core OF probing code.
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
>> - It seems several people tried to solve this in the core OF probing
>> code before, but the final solution never went in?
>> - This can be reproduced on other SoCs (e.g. sh73a0 and r8a7740) by
>> moving their pfc nodes before their interrupt controller nodes.
>> - This patch is against my working tree, so it doesn't apply to
>> Simon's repository, but you get the idea....
> No issues with the patch, but here are few comments on the core
> reasons (without looking at the code in this case) that might help
> fix similar issues.
> In all the cases I've seen these errors are caused by non-standard
> custom initcall levels for drivers like i2c bus. The real solution
> is to initialize drivers later with standard module_init, and stop
> the race to the bottom with custom initcall levels.
> If there is legacy board specific platofrm init code that needs
> i2c gpios early, that code can probably be moved to initialize
> later on.
In this case no i2c is involved. The drivers for both pinctrl
(renesas,pfc-r8a73a4) and irqchip (renesas,irqc) are registered
at the same level:
Hence the system uses the "natural" order from within the DTS,
and decided to instantiate the pfc before the irqchip.
> Also, there should not be any need for custom driver initcall
> levels from Linux generic framework point of view as for example
> irqchip implementing drivers work just fine as a loadable module.
As long as no other device that's instantiated earlier references that
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/