Re: [PATCH] RFC: interrupt consistency check for OF GPIO IRQs

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Am 12.09.2013 13:09, schrieb Alexander Holler:
Am 12.09.2013 12:28, schrieb Alexander Holler:
Am 12.09.2013 12:11, schrieb Javier Martinez Canillas:
On 09/12/2013 10:55 AM, Alexander Holler wrote:

...

By the way, how do you define two GPIOs/IRQs from different
gpio-banks/irq-controllers wuth that scheme?


That is indeed a very good question and I don't have a definite answer.

Would that be like below?

  ethernet@5,0 {
           compatible = "smsc,lan9221", "smsc,lan9115";
           interrupt-parent = <&gpio6>;
           interrupts = <16 8>;
           interrupt-parent = <&gpio7>;
           interrupts = <1 IRQF_TRIGGER_FALLING>; /* GPIO7_1 */
  };


...

So, if I understood the code correctly the DT IRQ core doesn't expect
a device
node to have more than one "interrupt-parent" property.

It *should* work though if you have multiple "interrupts" properties
defined and
all of them have the same "interrupt-parent":

        interrupt-parent = <&gpio6>;
        interrupts = <1 IRQF_TRIGGER_HIGH>; /* GPIO6_1 */
        interrupts = <2 IRQF_TRIGGER_LOW>; /* GPIO6_2 */

since of_irq_map_one() will be called for each "interrupts" and the
correct
"interrupt-parent" will get obtained by of_irq_find_parent().

I assumed that answer. So to make such a scenario possible, something
like this might be neccessary:

          interrupts = <&gpio6 1 IRQF_TRIGGER_HIGH>; /* GPIO6_1 */
          interrupts = <&gpio7 2 IRQF_TRIGGER_LOW>; /* GPIO7_2 */

or, to be compatible

          interrupts = <1 IRQF_TRIGGER_HIGH &gpio6>; /* GPIO6_1 */
          interrupts = <1 IRQF_TRIGGER_LOW &gpio7>; /* GPIO7_1 */

Another problem is the naming. In all the above cases, the driver would
not know which IRQ he should use for what. Maybe the order defines it,
but that wouldn't be very verbose. And I think just changing the name
would make travelling the tree impossible, as only the driver itself
would know the name and it's meaning.

On a second look, travelling the tree is still possible if the solution
would be like above (without that interrupt-parent). So if a driver
requires two interrupts he could use

       interrupt-foo = <1 IRQF_TRIGGER_HIGH &gpio6>; /* GPIO6_1 */
       interrupt-bar = <1 IRQF_TRIGGER_LOW &gpio7>; /* GPIO7_1 */

And travelling the tree will still be possible because walking from the
interrupt-controllers (those gpio) downwards would end up at the
interrupt definitions, so the name of them isn't needed to find them in
the tree.

I've just seen how they solved it for dma:

			dmas = <&edma0 16
				&edma0 17>;
			dma-names = "rx", "tx";

so it would be like

      interrupts = <1 IRQF_TRIGGER_HIGH &gpio6>; /* GPIO6_1 */
      interrupts = <1 IRQF_TRIGGER_LOW &gpio7>; /* GPIO7_1 */
      interrupt-names = "foo", "bar";

Or this would be possible:

      interrupt-parent = <&gpio6 &gpio7>;
      interrupts = <1 IRQF_TRIGGER_HIGH>; /* GPIO6_1 */
      interrupts = <1 IRQF_TRIGGER_LOW>; /* GPIO7_1 */
      interrupt-names = "foo", "bar";

Regards,

Alexander
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