Re: [PATCH v2 6/9] irqchip / gic: Add stacked irqdomain support for ACPI based GICv2 init
From: Hanjun Guo
Date: Fri Jul 03 2015 - 04:48:23 EST
On 06/30/2015 11:07 PM, Graeme Gregory wrote:
On Tue, Jun 30, 2015 at 01:17:14PM +0100, Marc Zyngier wrote:
On 30/06/15 12:50, Hanjun Guo wrote:
Hi Marc,
On 06/29/2015 04:39 PM, Marc Zyngier wrote:
On 27/06/15 04:52, Hanjun Guo wrote:
On 06/24/2015 01:38 AM, Lorenzo Pieralisi wrote:
On Tue, Jun 23, 2015 at 04:11:38PM +0100, Hanjun Guo wrote:
[...]
for (i = 0; i < nr_irqs; i++)
gic_irq_domain_map(domain, virq + i, hwirq + i);
@@ -945,11 +952,11 @@ void __init gic_init_bases(unsigned int gic_nr, int irq_start,
gic_irqs = 1020;
gic->gic_irqs = gic_irqs;
- if (node) { /* DT case */
+ if (node || !acpi_disabled) { /* DT or ACPI case */
gic->domain = irq_domain_add_linear(node, gic_irqs,
&gic_irq_domain_hierarchy_ops,
gic);
I think this is a bit more worrying, I mean passing a NULL node pointer to
the irqdomain layer which basically means you are booting out of ACPI
I'm little confused here, would you mind explaining more for your
worrying? To me, node pointer is optional and it's ok for ACPI
case.
(for you, if that's true for the irq_domain_add_linear implementation
that's another story), the node pointer should be optional but you
need feedback from IRQ layer maintainers here.
Sure.
Frankly, I'd really like to see ACPI using the "node" parameter for
something useful. This would save having to cache pointers all over the
place, will make find_irq_host() work as expected... etc.
See the comment at the top of linux/irqdomain.h :
"... This code could thus be used on other architectures by replacing
those two by some sort of arch-specific void * "token" used to identify
interrupt controllers."
To init GIC in ACPI, we can only use the table entry pointer as
the token, but the ACPI static tables are early mem/io remapped
memory at boot stage, and it will be not available after boot,
also we need muti types of MADT enties to init GIC (GICC and GICD
for GICv2, GICC or GICR and GICD for GICv3), not as DT, just
one single node to include all the information needed to init
the GIC.
A single pointer would be enough, you don't need all of them.
We use ACPI handle for devices as node for DT when the namespace
is available, but that's pretty late in the boot stage which GIC,
SMP and timers were already initialized, so ACPI handle can not
use as the token too.
I see multi places just pass NULL as the pointer directly for
irq_domain_add_linear() which works fine, and for ACPI, we tested
this patch and also it works.
Yes it works. But you're reinventing the wheel by keeping references
outside of the normal framework, which is simply going to make the code
more difficult to maintain in the long run.
Putting NULL as the device_node parameter really means "this is a domain
I don't need to look up later". In your case, you will have to lookup
that domain, all the time. You're just doing it in your own little
corner, which is what bothers me.
Hanjun, I think it should be possible that instead of looking up the
domains in our own bit of code. We can instead use a ptr to the
appropriate information as the token instead.
I don't think we have to replicate the behaviour of node, in the DT
case, but just do what is sensible for ACPI in this case.
I'm trying to introduce a pointer which point to the GICD when GIC
is initialized, this pointer will be used to match the irqdomain.
In driver code, I will find this pointer with the gsi, then find the
irqdomain match the pointer, then I hope I can remove acpi_irq_domain
in the end.
Marc, beyond this issue, do you have any more comments about this
patch set? the framework of init GIC? and the code to init GICV3?
if yes, I can address it along with this one together.
Thanks
Hanjun
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/