genirq: Correctly configure the trigger on chained interrupts

Commit 1e2a7d78499e ("irqdomain: Don't set type when mapping an IRQ")
moved the trigger configuration call from the irqdomain mapping to
the interrupt being actually requested.

This patch failed to handle the case where we configure a chained
interrupt, which doesn't get requested through the usual path.

In order to solve this, let's call __irq_set_trigger just before
starting the cascade interrupt. Special care must be taken to
make the flow handler stick, as the .irq_set_type method could
have reset it (it doesn't know we're dealing with a chained
interrupt).

Based on an initial patch by Jon Hunter.

Fixes: 1e2a7d78499e ("irqdomain: Don't set type when mapping an IRQ")
Reported-by: John Stultz <john.stultz@linaro.org>
Reported-by: Linus Walleij <linus.walleij@linaro.org>
Tested-by: John Stultz <john.stultz@linaro.org>
Acked-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index b4c1bc7c9ca204440c7c51e7df7a49b0c2ae511f..637389088b3f9cf88db58ce920350a3517a20ed2 100644 (file)
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -820,6 +820,17 @@ __irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle,
        desc->name = name;
 
        if (handle != handle_bad_irq && is_chained) {
+               /*
+                * We're about to start this interrupt immediately,
+                * hence the need to set the trigger configuration.
+                * But the .set_type callback may have overridden the
+                * flow handler, ignoring that we're dealing with a
+                * chained interrupt. Reset it immediately because we
+                * do know better.
+                */
+               __irq_set_trigger(desc, irqd_get_trigger_type(&desc->irq_data));
+               desc->handle_irq = handle;
+
                irq_settings_set_noprobe(desc);
                irq_settings_set_norequest(desc);
                irq_settings_set_nothread(desc);