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. Graeme -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html