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To: "Yang, Shunyong" <shunyong.yang@hxt-semitech.com>,
        "tglx@linutronix.de" <tglx@linutronix.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "Zheng, Joey" <yu.zheng@hxt-semitech.com>
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From: Marc Zyngier <marc.zyngier@arm.com>
Organization: ARM Ltd
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Date: Wed, 17 Jan 2018 09:56:18 +0000
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On 17/01/18 09:47, Yang, Shunyong wrote:
> Hi, Thomas,
> 
> On Wed, 2018-01-17 at 10:33 +0100, Thomas Gleixner wrote:
>> On Wed, 17 Jan 2018, Yang, Shunyong wrote:
>>
>>>
>>> Hi, Marc and Thomas,
>>>
>>> Thanks for your feedback.
>>>
>>> On Wed, 2018-01-17 at 10:18 +0100, Thomas Gleixner wrote:
>>>>
>>>> On Wed, 17 Jan 2018, Marc Zyngier wrote:
>>>>>
>>>>>
>>>>> In all honesty, I'd be more inclined to remove this debug
>>>>> feature
>>>>> altogether, as CONFIG_GENERIC_IRQ_DEBUGFS is more complete and
>>>>> more
>>>>> useful. Is there any feature missing from that infrastructure
>>>>> that
>>>>> prevents you from using it instead?
>>>>>
>>>>> If the answer is "none", then I'll post a patch removing it.
>>>> Wanted to do that quite some time ago and never came around to
>>>> it.
>>> I think they have different purpose.
>>> irq_domain_mapping is an overiew of the mapping of each virq to
>>> hwirq
>>> and the domain it belongs. It likes a map or index of each IRQs. I
>>> tend
>>> to suggest to keep it.
>> And how is that different from:
>>
>>>
>>> The nodes under debugfs irq/irqs describes information of every
>>> single
>>> irq.
>> Not at all. It contains the complete hierarchical information of each
>> virq.
>>
> I think irq_domain_mapping can provide some high-level information in a
> summary style.
> For example, we can check all the IRQs connect to a specific irq chip
> or irq domain.

You mean, something like this:

root@flakes:/sys/kernel/debug/irq# ls -l domains/
total 0
-r--r--r-- 1 root root 0 Jan  1  1970 default
-r--r--r-- 1 root root 0 Jan  1  1970 gpio@e0080000
-r--r--r-- 1 root root 0 Jan  1  1970 gpio@e1050000
-r--r--r-- 1 root root 0 Jan  1  1970 interrupt-controller@e1101000
-r--r--r-- 1 root root 0 Jan  1  1970 v2m@e0080000-2
-r--r--r-- 1 root root 0 Jan  1  1970 v2m@e0080000-3
-r--r--r-- 1 root root 0 Jan  1  1970 v2m@e0080000-4
root@flakes:/sys/kernel/debug/irq# grep -r v2m@e0080000-2 irqs/| cut -f1 -d:
irqs/49
irqs/48
irqs/47
irqs/46
irqs/45
irqs/44
irqs/43
irqs/42
irqs/41

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...