genirq: Restore trigger settings in irq_modify_status()

irq_modify_status starts by clearing the trigger settings from
irq_data before applying the new settings, but doesn't restore them,
leaving them to IRQ_TYPE_NONE.

That's pretty confusing to the potential request_irq() that could
follow. Instead, snapshot the settings before clearing them, and restore
them if the irq_modify_status() invocation was not changing the trigger.

Fixes: 1e2a7d78499e ("irqdomain: Don't set type when mapping an IRQ")
Reported-and-tested-by: jeffy <jeffy.chen@rock-chips.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Jon Hunter <jonathanh@nvidia.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20170818095345.12378-1-marc.zyngier@arm.com

diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
index a3cc37c..3675c60 100644 (file)
--- a/kernel/irq/chip.c
+++ b/kernel/irq/chip.c
@@ -1000,7 +1000,7 @@ EXPORT_SYMBOL_GPL(irq_set_chip_and_handler_name);
 
 void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 {
-       unsigned long flags;
+       unsigned long flags, trigger, tmp;
        struct irq_desc *desc = irq_get_desc_lock(irq, &flags, 0);
 
        if (!desc)
@@ -1014,6 +1014,8 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
 
        irq_settings_clr_and_set(desc, clr, set);
 
+       trigger = irqd_get_trigger_type(&desc->irq_data);
+
        irqd_clear(&desc->irq_data, IRQD_NO_BALANCING | IRQD_PER_CPU |
                   IRQD_TRIGGER_MASK | IRQD_LEVEL | IRQD_MOVE_PCNTXT);
        if (irq_settings_has_no_balance_set(desc))
@@ -1025,7 +1027,11 @@ void irq_modify_status(unsigned int irq, unsigned long clr, unsigned long set)
        if (irq_settings_is_level(desc))
                irqd_set(&desc->irq_data, IRQD_LEVEL);
 
-       irqd_set(&desc->irq_data, irq_settings_get_trigger_mask(desc));
+       tmp = irq_settings_get_trigger_mask(desc);
+       if (tmp != IRQ_TYPE_NONE)
+               trigger = tmp;
+
+       irqd_set(&desc->irq_data, trigger);
 
        irq_put_desc_unlock(desc, flags);
 }