Re: [PATCH 1/2] genirq: Get the fwnode back for irqchips being probed via ACPI namespace

From: Marc Zyngier
Date: Fri Jul 07 2017 - 04:17:53 EST

On 07/07/17 04:27, Hanjun Guo wrote:
> On 2017/7/6 21:05, Marc Zyngier wrote:
>> On 06/07/17 10:01, Hanjun Guo wrote:
>>> Hi Marc,
>>>
>>> On 2017/7/6 15:43, Marc Zyngier wrote:
>>>> On 06/07/17 05:35, Hanjun Guo wrote:
>>>>> From: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>>>>>
>>>>> commit d59f6617eef0 (genirq: Allow fwnode to carry name information only)
>>>>> forgot to do "domain->fwnode = fwnode;" for irqchips being probed via
>>>>> ACPI namesapce (DSDT/SSDT), that will break platforms with irqchip such
>>>>> as mbigen or qcom irq combiner, set the fwnode back to fix the issue.
>>>>>
>>>>> Reported-by: John Garry <john.garry@xxxxxxxxxx>
>>>>> Signed-off-by: Hanjun Guo <hanjun.guo@xxxxxxxxxx>
>>>>> ---
>>>>> kernel/irq/irqdomain.c | 3 +--
>>>>> 1 file changed, 1 insertion(+), 2 deletions(-)
>>>>>
>>>>> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
>>>>> index 14fe862..1bc38fa 100644
>>>>> --- a/kernel/irq/irqdomain.c
>>>>> +++ b/kernel/irq/irqdomain.c
>>>>> @@ -151,7 +151,6 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
>>>>> domain->flags |= IRQ_DOMAIN_NAME_ALLOCATED;
>>>>> break;
>>>>> default:
>>>>> - domain->fwnode = fwnode;
>>>>> domain->name = fwid->name;
>>>>> break;
>>>>> }
>>>>> @@ -172,7 +171,6 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
>>>>> strreplace(name, '/', ':');
>>>>>
>>>>> domain->name = name;
>>>>> - domain->fwnode = fwnode;
>>>>> domain->flags |= IRQ_DOMAIN_NAME_ALLOCATED;
>>>>> }
>>>>>
>>>>> @@ -196,6 +194,7 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
>>>>> INIT_RADIX_TREE(&domain->revmap_tree, GFP_KERNEL);
>>>>> domain->ops = ops;
>>>>> domain->host_data = host_data;
>>>>> + domain->fwnode = fwnode;
>>>>> domain->hwirq_max = hwirq_max;
>>>>> domain->revmap_size = size;
>>>>> domain->revmap_direct_max_irq = direct_max;
>>>>>
>>>> This doesn't seem right.
>>>>
>>>> Why is is_fwnode_irqchip() returning false when presented with an
>>>> irqchip probed via the ACPI namespace? That's what you should consider
>>>> fixing instead of moving that code around.
>>> irqchips probed via the ACPI namespace will have a fwnode handler
>>> with the fwnode type FWNODE_ACPI, similar to irqchips probed
>>> via DT having a fwnode handler with type FWNODE_OF, in this
>>> function with DT case, fwnode is set for irqdomain's fwnode,
>>> ACPI just reuse that code because they are similar.
>>>
>>> is_fwnode_irqchip() just checks if it's FWNODE_IRQCHIP, which is only
>>> available for irqchips probing via ACPI static tables such as ITS, GIC
>>> on ARM, or via DMAR on x86, those cases don't have a fwnode handler then
>>> need to create one via __irq_domain_alloc_fwnode(), which is different
>>> from DT/ACPI namesapce scan mechanism. So the patch above it's the best
>>> solution I got so far which just resume the code as before, correct me
>>> if you have something new :)
>> This violates the irqdomain API that takes two kind of fwnodes:
>> FWNODE_OF or FWNODE_IRQCHIP, and no others. You got away with it so
>> far, but it is over.
>>
>> You have two choices here: either you allocate a FWNODE_IRQCHIP in your
>> irqchip driver, and use this as a handle for your IRQ domain, or you
>> make the irqdomain code able to deal with any FWNODE_ACPI fwnode.
>
> Later one is better to me as allocate a FWNODE_IRQCHIP in the irqchip
> driver will override the FWNODE_ACPI handler.
>
>>
>> Does the following hack work for you?
>
> Yes, it works. shall we go this way with a proper fix?

I already have something written, together with name generation and stuff.

>
>>
>> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
>> index 14fe862aa2e3..37f4aa3985b3 100644
>> --- a/kernel/irq/irqdomain.c
>> +++ b/kernel/irq/irqdomain.c
>> @@ -155,6 +155,8 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
>> domain->name = fwid->name;
>> break;
>> }
>> + } else if (is_acpi_device_node(fwnode)) {
>> + domain->fwnode = fwnode;
>> } else if (of_node) {
>> char *name;
>>
>> If it does, we can then find weird and wonderful ways to give the
>> domain a shiny name in debugfs...
>
> How about the weird way below (using dev_name() which shows ACPI HID + number) ?
>
> +#include <linux/acpi.h>
> #include <linux/debugfs.h>
> +#include <linux/device.h>
> #include <linux/hardirq.h>
> #include <linux/interrupt.h>
> #include <linux/irq.h>
> @@ -172,6 +174,15 @@ struct irq_domain *__irq_domain_add(struct fwnode_handle *fwnode, int size,
>
> domain->name = name;
> domain->flags |= IRQ_DOMAIN_NAME_ALLOCATED;
> + } else if (is_acpi_device_node(fwnode)) {
> + struct acpi_device *adev = to_acpi_device_node(fwnode);
> +
> + domain->name = kstrdup(dev_name(&adev->dev), GFP_KERNEL);
> + if (!domain->name)
> + return NULL;
> +
> + domain->fwnode = fwnode;
> + domain->flags |= IRQ_DOMAIN_NAME_ALLOCATED;
> }
>
> But my hack code retrieving the ACPI data in irq domain core is really
> weird :)

Dunno. I'm using acpi_get_name() on the acpi handle, which seems to do
the right thing on a D05:

/sys/kernel/debug/irq/domains/
default irqchip@00000000c6000000-4 irqchip@000004006c000000-4 \_SB_.MBI1
irqchip@000000004c000000-2 irqchip@00000008c6000000-2 irqchip@00000400c6000000-2 \_SB_.MBI2
irqchip@000000004c000000-3 irqchip@00000008c6000000-3 irqchip@00000400c6000000-3 \_SB_.MBI3
irqchip@000000004c000000-4 irqchip@00000008c6000000-4 irqchip@00000400c6000000-4 \_SB_.MBI4
irqchip@000000006c000000-2 irqchip@000004004c000000-2 irqchip@00000408c6000000-2 \_SB_.MBI5
irqchip@000000006c000000-3 irqchip@000004004c000000-3 irqchip@00000408c6000000-3 \_SB_.MBI6
irqchip@000000006c000000-4 irqchip@000004004c000000-4 irqchip@00000408c6000000-4 \_SB_.MBI7
irqchip@00000000c6000000-2 irqchip@000004006c000000-2 irqchip@ffff000008000000 \_SB_.MBI8
irqchip@00000000c6000000-3 irqchip@000004006c000000-3 \_SB_.MBI0 \_SB_.MBI9

I'll post the patch later today.

M.
--
Jazz is not dead. It just smells funny...