Messages in this thread |  | | Date | Tue, 18 Nov 2014 17:26:42 +0800 | From | "Yun Wu (Abel)" <> | Subject | Re: [patch 04/16] genirq: Introduce irq_chip.irq_compose_msi_msg() to support stacked irqchip |
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On 2014/11/12 21:42, Thomas Gleixner wrote:
> From: Jiang Liu <jiang.liu@linux.intel.com> > > Add callback irq_compose_msi_msg to struct irq_chip, which will be used > to support stacked irqchip. > > Signed-off-by: Jiang Liu <jiang.liu@linux.intel.com> > Cc: Bjorn Helgaas <bhelgaas@google.com> > Cc: Grant Likely <grant.likely@linaro.org> > Cc: Marc Zyngier <marc.zyngier@arm.com> > Cc: Yingjoe Chen <yingjoe.chen@mediatek.com> > Cc: Yijing Wang <wangyijing@huawei.com> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > --- > include/linux/irq.h | 5 +++++ > kernel/irq/chip.c | 17 +++++++++++++++++ > 2 files changed, 22 insertions(+) > > diff --git a/include/linux/irq.h b/include/linux/irq.h > index 0adcbbbf2e87..536b7fc6c8f4 100644 > --- a/include/linux/irq.h > +++ b/include/linux/irq.h > @@ -29,6 +29,7 @@ struct seq_file; > struct module; > struct irq_desc; > struct irq_data; > +struct msi_msg; > typedef void (*irq_flow_handler_t)(unsigned int irq, > struct irq_desc *desc); > typedef void (*irq_preflow_handler_t)(struct irq_data *data); > @@ -320,6 +321,7 @@ static inline irq_hw_number_t irqd_to_hwirq(struct irq_data *d) > * any other callback related to this irq > * @irq_release_resources: optional to release resources acquired with > * irq_request_resources > + * @irq_compose_msi_msg: optional to compose message content for MSI > * @flags: chip specific flags > */ > struct irq_chip { > @@ -356,6 +358,8 @@ struct irq_chip { > int (*irq_request_resources)(struct irq_data *data); > void (*irq_release_resources)(struct irq_data *data); > > + void (*irq_compose_msi_msg)(struct irq_data *data, struct msi_msg *msg); > + > unsigned long flags; > }; > > @@ -443,6 +447,7 @@ extern void handle_percpu_devid_irq(unsigned int irq, struct irq_desc *desc); > extern void handle_bad_irq(unsigned int irq, struct irq_desc *desc); > extern void handle_nested_irq(unsigned int irq); > > +extern int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg); > #ifdef CONFIG_IRQ_DOMAIN_HIERARCHY > extern void irq_chip_ack_parent(struct irq_data *data); > extern int irq_chip_retrigger_hierarchy(struct irq_data *data); > diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c > index 12f3e72449eb..8f362db17a8a 100644 > --- a/kernel/irq/chip.c > +++ b/kernel/irq/chip.c > @@ -867,3 +867,20 @@ int irq_chip_retrigger_hierarchy(struct irq_data *data) > return -ENOSYS; > } > #endif > + > +int irq_chip_compose_msi_msg(struct irq_data *data, struct msi_msg *msg) > +{ > + struct irq_data *pos = NULL; > + > +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY > + for (; data; data = data->parent_data) > +#endif > + if (data->chip && data->chip->irq_compose_msi_msg) > + pos = data; > + if (!pos) > + return -ENOSYS; > + > + pos->chip->irq_compose_msi_msg(pos, msg); > + > + return 0; > +}
Adding message composing routine to struct irq_chip is OK to me, and it should be because it is interrupt controllers' duty to compose messages (so that they can parse the messages correctly without any pre-defined rules that endpoint devices absolutely need not to know). However a problem comes out when deciding which parameters should be passed to this routine. A message can associate with multiple interrupts, which makes me think composing messages for each interrupt is not that appropriate. And we can take a look at the new routine irq_chip_compose_msi_msg(). It is called by msi_domain_activate() which will be called by irq_domain_activate_irq() in irq_startup() for each interrupt descriptor, result in composing a message for each interrupt, right? (Unless requiring a judge on the parameter @data when implementing the irq_compose_msi_msg() callback that only compose message for the first entry of that message. But I really don't like that...)
Regards, Abel
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