[PATCH RFC] irq-bcm2836: Avoid "Invalid trigger warning"

[Marc Zyngier]

On 16/11/17 17:53, Phil Elwell wrote:
> Hi Stefan,
> 
> On 16/11/2017 17:34, Stefan Wahren wrote:
>> Hi Phil,
>>
>>> Marc Zyngier <marc.zyngier at arm.com> hat am 16. November 2017 um 09:57 geschrieben:
>>>
>>>
>>> On Thu, Nov 16 2017 at  7:53:02 am GMT, Stefan Wahren <stefan.wahren at i2se.com> wrote:
>>>> From: Phil Elwell <phil at raspberrypi.org>
>>>>
>>>> Initialise the level for each IRQ to avoid a warning from the
>>>> arm arch timer code:
>>>>
>>>>     arch_timer: WARNING: Invalid trigger for IRQ19, assuming level low
>>>>     arch_timer: WARNING: Please fix your firmware
>>>>     arch_timer: cp15 timer(s) running at 19.20MHz (virt).
>>>>
>>>> Signed-off-by: Phil Elwell <phil at raspberrypi.org>
>>>> Signed-off-by: Stefan Wahren <stefan.wahren at i2se.com>
>>>> ---
>>>>  drivers/irqchip/irq-bcm2836.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/irqchip/irq-bcm2836.c b/drivers/irqchip/irq-bcm2836.c
>>>> index 667b9e1..abc9b40 100644
>>>> --- a/drivers/irqchip/irq-bcm2836.c
>>>> +++ b/drivers/irqchip/irq-bcm2836.c
>>>> @@ -104,7 +104,7 @@ static void bcm2836_arm_irqchip_register_irq(int hwirq, struct irq_chip *chip)
>>>>  
>>>>  	irq_set_percpu_devid(irq);
>>>>  	irq_set_chip_and_handler(irq, chip, handle_percpu_devid_irq);
>>>> -	irq_set_status_flags(irq, IRQ_NOAUTOEN);
>>>> +	irq_set_status_flags(irq, IRQ_NOAUTOEN | IRQ_TYPE_LEVEL_LOW);
>>>>  }
>>>>  
>>>>  static void
>>>
>>> Why is this only done for the per-cpu interrupts? I can't see what
>>> guarantees the same thing for global interrupts...
>>
>> i don't know. Could you please answer?
>>
>> I'm only interested to get the rid of this ugly warning ...
>>
>> and the right fix ;-)
> 
> That was my motivation too, with a preference for the smallest change that had
> the desired effect.
> 
> The warning message comes from the arch_timer code, which only cares about the
> interrupts it has been configured to use. Since these are all per-cpu
> interrupts, the state of the global interrupts is irrelevant.

The fact that no driver screams about it doesn't make it right. You're
being bitten by the lack of interrupt polarity description in your DT.
That is fine as long as you only support one type, but you need to tell
the core code what you're doing.

Your whole interrupt registration thing is already quite a departure
from the normal flow, where the interrupt should be created via the DT
parsing code, and not eagerly like it is done here. I'd rather you
address it by using the expected flow for a DT platform, with a xlate
method that returns the actual trigger type (I assume all interrupts on
this system are level...).

The same issue is present in the bcm2835 interrupt controller, which
seems to be the one implementing global interrupts.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...