On 2014/11/24 22:11, Jiang Liu wrote:
> On 2014/11/24 22:01, Yun Wu (Abel) wrote:
>> On 2014/11/24 21:13, Thomas Gleixner wrote:
>>
>>> On Mon, 24 Nov 2014, Yun Wu (Abel) wrote:
>>>> Hi Thomas, Jiang,
>>>> On 2014/11/12 21:42, Thomas Gleixner wrote:
>>>>
>>>>> From: Jiang Liu <jiang....@linux.intel.com>
>>>>>
>>>> [...]
>>>>> /* Number of irqs reserved for a legacy isa controller */
>>>>> #define NUM_ISA_INTERRUPTS 16
>>>>> @@ -64,6 +66,16 @@ struct irq_domain_ops {
>>>>> int (*xlate)(struct irq_domain *d, struct device_node *node,
>>>>> const u32 *intspec, unsigned int intsize,
>>>>> unsigned long *out_hwirq, unsigned int *out_type);
>>>>> +
>>>>> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
>>>>> + /* extended V2 interfaces to support hierarchy irq_domains */
>>>>> + int (*alloc)(struct irq_domain *d, unsigned int virq,
>>>>> + unsigned int nr_irqs, void *arg);
>>>>> + void (*free)(struct irq_domain *d, unsigned int virq,
>>>>> + unsigned int nr_irqs);
>>>>> + void (*activate)(struct irq_domain *d, struct irq_data *irq_data);
>>>>> + void (*deactivate)(struct irq_domain *d, struct irq_data *irq_data);
>>>>
>>>> What's the usage of the parameter domain reference in activate/deactivate?
>>>> I think the purpose of the two callbacks is to activate/deactivate the
>>>> irq_data->hwirq in irq_data->domain. If so, the first parameter @domain is
>>>> required to be equal to irq_data->domain (which makes @domain useless).
>>>> Besides, the main responsibility of interrupt domains is to manage mappings
>>>> between hardware and linux interrupt numbers, so would it be better if move
>>>> the two callbacks into struct irq_chip?
>>>
>>> No. It's not a function of the irq_chip to activate/deactivate a
>>> hierarchy. As I explained you before:
>>>
>>> The existing irqdomain code maps between hardware and virtual
>>> interrupts and thereby activates the interrupt in hardware.
>>>
>>> In the hierarchical case we do not touch the hardware in the
>>> allocation step, so we need to activate the allocated interrupt in the
>>> hardware before we can use it. And that's clearly a domain interface
>>> not a irq chip issue.
>>>
>>
>> Makes sense, now the interrupt domain seems to be the best place.
>> And when the @domain parameter can be really useful? I haven't see
>> anyone using it so far.
> We will use it for IOAPIC on x86, as below:
> void mp_irqdomain_deactivate(struct irq_domain *domain,
> struct irq_data *irq_data)
> {
> ioapic_mask_entry(mp_irqdomain_ioapic_idx(domain),
> (int)irq_data->hwirq);
> }
>
>>From an object oriented point of view, we pass the object as the
> first parameter. It's true that we could retrieve domain from
> irq_data->domain instead of explicitly passing it in, but that
> will cause irqdomain interfaces depends on irq_data, not sounds
> a good situation:)
Hi Gerry,
Is there any possibility that domain doesn't equal to irq_data->domain?
I'm a little confused..
Thanks,
Abel
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