omap: IORESOURCE_IRQ flags not set when defining a GPIO-IRQ from DT

Javier Martinez Canillas martinez.javier at
Fri Mar 1 11:17:57 EST 2013

Hi Jon,

NOTE: I'm changing $subject to something more relevant to stop adding
noise on the original thread.

On Thu, Feb 28, 2013 at 9:49 PM, Jon Hunter <jon-hunter at> wrote:
> On 02/28/2013 06:17 AM, Javier Martinez Canillas wrote:
>> On Thu, Feb 28, 2013 at 12:16 AM, Jon Hunter <jon-hunter at> wrote:
>>> On 02/26/2013 09:57 PM, Javier Martinez Canillas wrote:
>>> [snip]
>>>> Something like that would definitely solve the GPIO request issue but
>>>> we still have the issue that the current OMAP GPIO controller binding
>>>> does not support #interrupt-cells = <2>.
>>>> So, we can't pass the trigger type and level flags for an IRQ-GPIO
>>>> when using an GPIO controller as the interrupt-parent for a device
>>>> node.
>>>> Do you have any comments on that issue?
>>> Can you elaborate a bit more on why you say this is not supported?
>>> I have been playing with this today on an omap board and if I set the
>>> #interrupt-cells = <2>, then I do see that irq_domain_xlate_onetwocell()
>>> is called and the irq number and flags read as expected. Following which
>>> I then see it will call the omap_irq_type() to set type. So AFAICT it works.
>> Yes, it does.
>> I (wrongly) assumed that it was not working since the GPIO OMAP
>> binding documentation says that #interrupt-cells should be <2> but all
>> OMAP2+ DTs use <1> instead. Also, when trying to change to <2> I had
>> the kernel hang.
>> But it was indeed that the GPIO bank was not enabled before calling
>> gpio_irq_type() and this made the kernel to hang. Your patch fixed the
>> issue and allowed me to find the cause.
>> The problem was that when using the DT hack of defining the GPIO in
>> the ethernet chip regulator,  the calls to
>> irq_domain_xlate_onetwocell() and gpio_irq_type() were made before the
>> call to gpio_request_one() so the GPIO bank was not enabled.
>> If gpio_request() is called in gpmc_probe_dt(), then the GPIO bank is
>> enabled and gpio_irq_type() succeeds.
>> So, it was just me being stupid and don't understanding the implementation.
> No problem. Glad we are on the same page :-)
>>> Please note I do see that when the SMC driver calls request_irq() in
>>> smc_drv_probe() it is also settings the trigger type to
>>> IRQ_TYPE_EDGE_RISING (default). So if you are setting to low-level
>>> sensitive in DT, then this is being overwritten. We could fix this by
>>> setting SMC_IRQ_FLAGS to -1 for OMAP.
>> Please note that I'm using a SMSC 911x chip and not a SMSC 91x, so the
>> driver is not smc91x but smc911x. It has the same behaviour though
>> (IRQ flags overwritten somehow), just to be sure that we are on the
>> same page.
>> I don't know if just setting SMC_IRQ_FLAGS to -1 will be enough to fix
>> the smc91x since request_irq() is just passing whatever value is in
>> irq_flags.
>> By looking at the two drivers (smc91x and smsc911x) it seems that the
>> only difference on how they manage the flags is that smc91x does:
>> unsigned long irq_flags = SMC_IRQ_FLAGS;
>> ...
>>        if (irq_flags == -1 || ires->flags & IRQF_TRIGGER_MASK)
>>                 irq_flags = ires->flags & IRQF_TRIGGER_MASK;
>> while smsc911x driver's probe function uses the flags from the
>> resource unconditionally:
>> irq_flags = irq_res->flags & IRQF_TRIGGER_MASK;
>> So, at the end both will set irq_flags to whatever is on the
>> IORESOURCE_IRQ struct resource flags member.
> Actually, that's not the case for smc91x. By default SMC_IRQ_FLAGS != -1
> (for omap) and so it will not set irq_flags to ires->flags &
> IRQF_TRIGGER_MASK. However, if I force irq_flags to be -1, then I see
> that irq_flags are to 0.

Yes, I meant that the behaviour is the same if you define
SMC_IRQ_FLAGS to -1 for omap.

>> The real problem is irq_flags to be 0 instead of the value defined on
>> the second cell of the "interrupts" property.
> So the resource flags for each irq is set in
> of_irq_to_resource() which just does ...
>         r->start = r->end = irq;
>         r->flags = IORESOURCE_IRQ;
>         r->name = name ? name : dev->full_name;
> of_irq_to_resource() calls irq_to_parse_and_map() which eventually just
> calls irq_set_irq_type() but type/flags is not returned and not populated.
> I am wondering if this is intentional.

Indeed, I was wondering the same.

>The irq_type is being correctly
> configured by irq_set_irq_type() when of_irq_to_resource() is called. In
> the smc driver, if irq_flags are 0, then when request_irq() is called
> the trigger type will not be set again (which is ok). __setup_irq has
> the following ...
>         /* Setup the type (level, edge polarity) if configured: */
>         if (new->flags & IRQF_TRIGGER_MASK) {
>                 ret = __irq_set_trigger(desc, irq,
>                         new->flags & IRQF_TRIGGER_MASK);
> Cheers
> Jon

I'll try to take a deeper look to this later next week.

Thanks a lot for your help!


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