linux-kernel - Re: [PATCH v3 1/3] genirq: add support for per-cpu dev

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Date:	Fri, 30 Sep 2011 12:08:01 +0100
From:	Marc Zyngier <marc.zyngier@....com>
To:	Abhijeet Dharmapurikar <adharmap@...eaurora.org>
CC:	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH v3 1/3] genirq: add support for per-cpu dev_id interrupts

On 29/09/11 06:56, Abhijeet Dharmapurikar wrote:
> On 09/23/2011 09:03 AM, Marc Zyngier wrote:
>> The ARM GIC interrupt controller offers per CPU interrupts (PPIs),
>> which are usually used to connect local timers to each core.
>> Each CPU has its own private interface to the GIC,
>> and only sees the PPIs that are directly connect to it.
>>
>> While these timers are separate devices and have a separate
>> interrupt line to a core, they all use the same IRQ number.
>>
>> For these devices, request_irq() is not the right API as it
>> assumes that an IRQ number is visible by a number of CPUs
>> (through the affinity setting), but makes it very awkward to
>> express that an IRQ number can be handled by all CPUs, and
>> yet be a different interrupt line on each CPU, requiring a
>> different dev_id cookie to be passed back to the handler.
>>
>> The *_percpu_irq() functions is designed to overcome these
>> limitations, by providing a per-cpu dev_id vector:
>>
>> int request_percpu_irq(unsigned int irq, irq_handler_t handler,
>> 		   const char *devname, void __percpu *percpu_dev_id);
>> void free_percpu_irq(unsigned int, void __percpu *);
>> int setup_percpu_irq(unsigned int irq, struct irqaction *new);
>> void remove_percpu_irq(unsigned int irq, struct irqaction *act);
>> void enable_percpu_irq(unsigned int irq);
> 
> As mentioned here
> https://lkml.org/lkml/2011/9/25/121
> 
> can we add irqflags to enable_percpu_irq? This will make msm's
> usage cleaner and it wont have to rely on accessing the gic
> registers outside the driver.

I have the attached patch in my tree (and obviously hacked the
corresponding timer code).

Can you give it a whirl by removing your private GIC configuration and
passing the type to enable_percpu_irq()?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...
View attachment "0001-genirq-percpu-allow-interrupt-type-to-be-set-at-enab.patch" of type "text/x-patch" (2147 bytes)