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

[Phil Elwell]

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.

Phil