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 <[email protected]> >>>> >>> [...] >>>> /* 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:) Thanks! Gerry > > Thanks, > Abel > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
