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SubjectRe: [patch 07/16] genirq: Introduce helper irq_domain_set_info() to reduce duplicated code
On 2014/11/14 23:31, Marc Zyngier wrote:
> On 12/11/14 13:43, Thomas Gleixner wrote:
>> From: Jiang Liu <jiang.liu@linux.intel.com>
>>
>> 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/irqdomain.h | 5 +++++
>> kernel/irq/irqdomain.c | 10 ++++++++++
>> 2 files changed, 15 insertions(+)
>>
>> Index: tip/include/linux/irqdomain.h
>> ===================================================================
>> --- tip.orig/include/linux/irqdomain.h
>> +++ tip/include/linux/irqdomain.h
>> @@ -33,6 +33,7 @@
>> #define _LINUX_IRQDOMAIN_H
>>
>> #include <linux/types.h>
>> +#include <linux/irqhandler.h>
>> #include <linux/radix-tree.h>
>>
>> struct device_node;
>> @@ -263,6 +264,10 @@ extern int irq_domain_set_hwirq_and_chip
>> irq_hw_number_t hwirq,
>> struct irq_chip *chip,
>> void *chip_data);
>> +extern void irq_domain_set_info(struct irq_domain *domain, unsigned int virq,
>> + irq_hw_number_t hwirq, struct irq_chip *chip,
>> + void *chip_data, irq_flow_handler_t handler,
>> + void *handler_data, const char *handler_name);
>> extern void irq_domain_reset_irq_data(struct irq_data *irq_data);
>> extern void irq_domain_free_irqs_common(struct irq_domain *domain,
>> int virq, int nr_irqs);
>> Index: tip/kernel/irq/irqdomain.c
>> ===================================================================
>> --- tip.orig/kernel/irq/irqdomain.c
>> +++ tip/kernel/irq/irqdomain.c
>> @@ -882,6 +882,16 @@ int irq_domain_set_hwirq_and_chip(struct
>> return 0;
>> }
>>
>> +void irq_domain_set_info(struct irq_domain *domain, unsigned int virq,
>> + irq_hw_number_t hwirq, struct irq_chip *chip,
>> + void *chip_data, irq_flow_handler_t handler,
>> + void *handler_data, const char *handler_name)
>> +{
>> + irq_domain_set_hwirq_and_chip(domain, virq, hwirq, chip, chip_data);
>> + __irq_set_handler(virq, handler, 0, handler_name);
>> + irq_set_handler_data(virq, handler_data);
>> +}
>> +
>
> We still have the issue that, depending on where in the stack this is
> called, this will succeed or fail: If this is called from the inner
> irqchip, __irq_set_handler() will fail, as it will look at the outer
> domain as the (desc->irq_data.chip == &no_irq_chip) test fails (we
> haven't set the top level yet).
>
> I have this very imperfect workaround in my tree:
>
> diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c
> index d028b34..91e6515 100644
> --- a/kernel/irq/chip.c
> +++ b/kernel/irq/chip.c
> @@ -731,7 +731,16 @@ __irq_set_handler(unsigned int irq, irq_flow_handler_t handle, int is_chained,
> if (!handle) {
> handle = handle_bad_irq;
> } else {
> - if (WARN_ON(desc->irq_data.chip == &no_irq_chip))
> +#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
> + struct irq_data *irq_data = &desc->irq_data;
> + while (irq_data) {
> + if (irq_data->chip != &no_irq_chip)
> + break;
> + irq_data = irq_data->parent_data;
> + }
> +#endif
> +
> + if (WARN_ON(!irq_data || irq_data->chip == &no_irq_chip))
> goto out;
> }
>
> Which translate into: If there is at least one irqchip in the domain,
> it will probably sort itself out. Not ideal. Any real solution to
> this problem?
>
> GICv2 faces this exact problem, as some of its interrupts are used
> directly, and some others are used through the MSI domain. In the
> GIC driver, it is almost impossible to find out...
Hi Marc,
I prefer the above solution to relax the warning conditions.
Changing the calling order in irq_domain_ops->alloc() looks a little
strange, and other interrupt drivers may still run into the same issue.
Regards!
Gerry

>
> Thanks,
>
> M.
>


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