Hi Marc,


2017-09-07 21:25 GMT+09:00 Marc Zyngier [off-list ref]:

On 07/09/17 12:41, Masahiro Yamada wrote:

quoted

Prior to the addition of irq_domain_push_irq(), the hierarchy
IRQ domain always allocates IRQs from the outer-most domain.
Each irqchip usually calls irq_domain_alloc_irqs_parent(),
ascending the topology up to the root irqchip.

The brand-new function irq_domain_push_irq() allows us to allocate
IRQs for parent domain first, then add a child irq_data to the
tail of the chain.

For the new use-case, if the parent sets a temporary trigger type,
it may differ from the type requested to the outer-most irqchip,
then irq_create_fwspec_mapping() warns "type mismatch, failed to map..."

Clear the trigger type when a new irq_data is connected to the chain.

Signed-off-by: Masahiro Yamada <redacted>
---

Changes in v4:
  - Newly added


 kernel/irq/irqdomain.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index da3e0b6..18d11b9 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c

@@ -1532,6 +1532,9 @@ int irq_domain_push_irq(struct irq_domain *domain, int virq, void *arg)
      tail_irq_data->chip = NULL;
      tail_irq_data->chip_data = NULL;

+     /* clear the trigger type to avoid "type mismatch" error */
+     irqd_set_trigger_type(tail_irq_data, IRQ_TYPE_NONE);
+

This feels wrong. The initial interrupt hierarchy does have a set
trigger, because it has been configured already, and switching it to
NONE is hiding the fact that you're setting it to another, conflicting
value.

Your new fwspec should have a type that is really compatible with with
the underlying interrupt, however "temporary". If it is not, you have a
problem.

My motivation is to describe interrupt connection by
DT property, like follows:

interrupts = <48 4>, <49 4>, <50 4>, <51 4>,
        <52 4>, <53 4>, <54 4>, <55 4>,
        <56 4>, <57 4>, <58 4>, <59 4>,
        <60 4>, <61 4>, <62 4>, <63 4>,
        <154 4>, <155 4>, <156 4>, <157 4>,
        <158 4>;


The number of cells is fixed, so I need to
give something as the second parameter.

The "4" may not be a real trigger type,
it is just a temporal value to fill the space.


The device may pass a different trigger type
when it calls gpio_to_irq() && request_irq().
I cannot know the real trigger type until the device is probed.


Having said that, if this is a bad idea,
I will consider a different approach for my GPIO driver.


-- 
Best Regards
Masahiro Yamada
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