Re: [Bugfix] x86, irq: Fix bug in setting IOAPIC pin attributes

[Mika Westerberg <mika.westerberg@linux.intel.com>]

On Tue, Aug 26, 2014 at 04:45:01PM +0800, Jiang Liu wrote:
> On startup, IOAPIC driver preallocates IRQ descriptors and programs
> IOAPIC pins with default level and polarity attributes for all legacy
> IRQs. Later legacy IRQ users may fail to set IOAPIC pin attributes
> if the requested attributes conflicts with the default IOAPIC pin
> attributes. So change mp_irqdomain_map() to allow the first legacy IRQ
> user to reprogram IOAPIC pin with different attributes.
> 
> Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com>

I tried this and now we get further in setting up the IOAPIC but it
still doesn't work :-(

I noticed that mp_set_gsi_attr() never programs the IOAPIC in case
info->set is 0 so I added following on top of your patch. With the below
patch, the system seems to work as expected.

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index 66c2700c9f83..777762a0ad09 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -3942,10 +3942,16 @@ int mp_set_gsi_attr(u32 gsi, int trigger, int polarity, int node)
 
 	mutex_lock(&ioapic_mutex);
 	if (!info->set) {
+		struct io_apic_irq_attr attr;
+
 		info->trigger = trigger;
 		info->polarity = polarity;
 		info->node = node;
 		info->set = 1;
+
+		/* Now program the IOAPIC with the new attributes */
+		set_io_apic_irq_attr(&attr, ioapic, pin, trigger, polarity);
+		ret = io_apic_setup_irq_pin(gsi, node, &attr);
 	} else if (info->trigger != trigger || info->polarity != polarity) {
 		ret = -EBUSY;
 	}