linux-kernel - Re: [PATCH 3/9] irq: convert generic-chip to use irq

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Message-ID: <4EEA1DA8.6040705@gmail.com>
Date:	Thu, 15 Dec 2011 10:17:44 -0600
From:	Rob Herring <robherring2@...il.com>
To:	Grant Likely <grant.likely@...retlab.ca>
CC:	Shawn Guo <shawn.guo@...escale.com>, Kevin Hilman <khilman@...com>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Tony Lindgren <tony@...mide.com>,
	Linus Walleij <linus.ml.walleij@...il.com>,
	devicetree-discuss@...ts.ozlabs.org, linux-kernel@...r.kernel.org,
	Rob Herring <rob.herring@...xeda.com>,
	Barry Song <baohua.song@....com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 3/9] irq: convert generic-chip to use irq_domain

On 12/15/2011 09:55 AM, Grant Likely wrote:
> On Thu, Dec 15, 2011 at 6:56 AM, Rob Herring <robherring2@...il.com> wrote:
>> Shawn,
>>
>> On 12/15/2011 07:39 AM, Rob Herring wrote:
>>> On 12/14/2011 11:55 PM, Shawn Guo wrote:
>>>> On Thu, Dec 15, 2011 at 01:25:20PM +0800, Shawn Guo wrote:
>>>>> On Wed, Dec 14, 2011 at 09:28:52AM -0600, Rob Herring wrote:
>>>>>> From: Rob Herring <rob.herring@...xeda.com>
>>>>>>
>>>>>> Add irq domain support to irq generic-chip. This enables users of
>>>>>> generic-chip to support dynamic irq assignment needed for DT interrupt
>>>>>> binding. Users must be converted to use irq_data.hwirq for determining
>>>>>> local interrupt numbers rather than using the Linux irq number.
>>>>>>
>>>>>> irq_base is kept for now as there are a few users of it. Once they
>>>>>> are converted to use the irq domain, it can be removed.
>>>>>>
>>>>>> Signed-off-by: Rob Herring <rob.herring@...xeda.com>
>>>>>> Cc: Thomas Gleixner <tglx@...utronix.de>
>>>>>> ---
>>>>>
>>>>> Tested-by: Shawn Guo <shawn.guo@...aro.org>
>>>>>
>>>> Sorry, I have to take that tag back after I correct my test setup.
>>>> It does not work for imx5 TZIC case, because the following change
>>>> I suggested before is missed.
>>>>
>>>> diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
>>>> index eb763f7..2a2aac1 100644
>>>> --- a/kernel/irq/irqdomain.c
>>>> +++ b/kernel/irq/irqdomain.c
>>>> @@ -39,7 +39,7 @@ void irq_domain_add(struct irq_domain *domain)
>>>>                         return;
>>>>                 }
>>>>                 d->domain = domain;
>>>> -               d->hwirq = hwirq;
>>>> +               d->hwirq = hwirq - domain->hwirq_base;
>>>
>>> This is a problem. It entirely defeats the point of hwirq_base and it
>>> would break the GIC. We need to fix this in the generic irq chip.
>>>
>>
>> I think I found a fix. Can you try 's/d->hwirq/(d->hwirq % 32)/' in
>> generic-chip.c.
> 
> Ugh, but that hard codes an assumption that a domain cannot have more
> that 32 irqs.
> 
> /me goes to dig into irq_domain code...

No, it hard codes that generic irq chip is 32 interrupts at most which
is already the case. That's why the TZIC uses 5 generic irq chip instances.

Rob
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