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SubjectRe: [PATCH v3 22/25] irq_domain/x86: Convert x86 (embedded) to use common irq_domain
On Wed, Feb 1, 2012 at 11:06 AM, Grant Likely <grant.likely@secretlab.ca> wrote:
> On Wed, Feb 1, 2012 at 7:17 AM, Sebastian Andrzej Siewior
> <bigeasy@linutronix.de> wrote:
>> * Grant Likely | 2012-01-30 12:58:42 [-0700]:
>>
>>>Ugh.  This isn't easy.  The legacy mapping really needs all the
>>
>> Feel free to merge this patch. I don't have the time to look at this now
>> so I take a look at the ioapic later.
>
> There's no rush here.  I can leave it as-is with IRQ_DOMAIN turned off
> for x86 for now.

Turns out I have to enable IRQ_DOMAIN for x86 because the TI TWL4030
driver needs it. I do need to apply this patch. Until something
better can be implemented, can I change ioapic_add_ofnode() so that it
allocates all irq_descs immediately. It's not ideal, but every other
approach I've looked at results in nasty hacks.

Looking at the ioapic code, it appears to handle preallocated
irq_descs gracefully.

Does adding this loop help (apologies if it is whitespace damaged, I
cut&paste it):

diff --git a/arch/x86/kernel/devicetree.c b/arch/x86/kernel/devicetree.c
index 3ae2ced..89c1310 100644
--- a/arch/x86/kernel/devicetree.c
+++ b/arch/x86/kernel/devicetree.c
@@ -345,7 +345,7 @@ const struct irq_domain_ops ioapic_irq_domain_ops = {
static void __init ioapic_add_ofnode(struct device_node *np)
{
struct resource r;
- int i, ret;
+ int i, j, ret;

ret = of_address_to_resource(np, 0, &r);
if (ret) {
@@ -361,6 +361,14 @@ static void __init ioapic_add_ofnode(struct
device_node *np)

gsi_cfg = mp_ioapic_gsi_routing(i);

+ /*
+ * Preallocate irq_descs so that the legacy mapping
+ * works, but don't set them up.
+ * io_apic_setup_irq_pin_once() will finish the set up.
+ */
+ for (j = 0; j < 32; j++)
+ irq_alloc_desc_at(gsi_cfg->gsi_base + j,
+ cpu_to_node(0));
id = irq_domain_add_legacy(np, 32, gsi_cfg->gsi_base, 0,
&ioapic_irq_domain_ops,
(void*)i);

g.
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