Subject: Re: [RFC PATCH V2 1/8] irqdomain: Ensure type settings match for an
 existing mapping
To: Linus Walleij <linus.walleij@linaro.org>,
        Jon Hunter <jonathanh@nvidia.com>
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CC: Thomas Gleixner <tglx@linutronix.de>, Jason Cooper <jason@lakedaemon.net>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Jiang Liu <jiang.liu@linux.intel.com>,
        Stephen Warren <swarren@wwwdotorg.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Kevin Hilman <khilman@kernel.org>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Soren Brinkmann <soren.brinkmann@xilinx.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-tegra@vger.kernel.org" <linux-tegra@vger.kernel.org>
From: Grygorii Strashko <grygorii.strashko@ti.com>
Message-ID: <5679347C.6030405@ti.com>
Date: Tue, 22 Dec 2015 13:31:08 +0200
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On 12/22/2015 12:00 PM, Linus Walleij wrote:
> On Tue, Dec 22, 2015 at 10:58 AM, Linus Walleij
> <linus.walleij@linaro.org> wrote:
>> On Fri, Dec 18, 2015 at 11:10 AM, Jon Hunter <jonathanh@nvidia.com> wrote:
>>> On 17/12/15 13:16, Linus Walleij wrote:
>>>> On Thu, Dec 17, 2015 at 11:48 AM, Jon Hunter <jonathanh@nvidia.com> wrote:
>>>>> +               } else {
>>>>> +                       virq = irq_domain_alloc_descs(-1, 1, hwirq,
>>>>> +                                                     of_node_to_nid(of_node));
>>>>
>>>> What is this all of a sudden? Not even mentioned in the
>>>> commit. Plus I bet ACPI need something else than OF nid
>>>> passed here.
>>>
>>> Do you mean the else part of all of the above?
>>
>> Yes
>>
>>> So in the current code, the else part calls irq_create_mapping() (...)
>>
>> No, not that... The fact that you all of a sudden have started
>> calling irq_domain_alloc_descs() which the function didn't do
>> before, totally changing the calling semantics for everyone in
>> the kernel, leading to the problem I then describe with this
>> potentially being called before the irqdomain for the irqchip
>> is initialized and descs getting "random" numbers.
> 
> I see I didn't go into those details in my first answer. Hm, I
> guess I got uncertain and deleted it because I remember
> writing it...
> 
> I am simply worries that starting to call irq_domain_alloc_descs()
> has unintended side effects, especially on platforms using
> legacy or simple irqdomains.
> 

I think, some misunderstanding here introduced by replacing
irq_create_mapping() call on subset of direct calls to
irq_domain_alloc_descs() and irq_domain_associate().

-- 
regards,
-grygorii
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