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From:   Sergey Shtylyov <s.shtylyov@omp.ru>
Subject: Re: [PATCH v2] platform: finally disallow IRQ0 in platform_get_irq()
 and its ilk
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
CC:     "Rafael J. Wysocki" <rafael@kernel.org>,
        <linux-kernel@vger.kernel.org>, Marc Zyngier <maz@kernel.org>
References: <025679e1-1f0a-ae4b-4369-01164f691511@omp.ru>
 <YmfNi3j/sL9PdByv@kroah.com>
Organization: Open Mobile Platform
Message-ID: <d0a51ca4-e535-01cc-fb08-2a59ad2e50dd@omp.ru>
Date:   Wed, 27 Apr 2022 21:59:41 +0300
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Hello!

On 4/26/22 1:46 PM, Greg Kroah-Hartman wrote:

>> The commit a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is
>> invalid") only calls WARN() when IRQ0 is about to be returned, however
>> using IRQ0 is considered invalid (according to Linus) outside the arch/
>> code where it's used by the i8253 drivers. Many driver subsystems treat
>> 0 specially (e.g. as an indication of the polling mode by libata), so
>> the users of platform_get_irq[_byname]() in them would have to filter
>> out IRQ0 explicitly and this (quite obviously) doesn't scale...
>> Let's finally get this straight and return -EINVAL instead of IRQ0!
>>
>> Fixes: a85a6c86c25b ("driver core: platform: Clarify that IRQ 0 is invalid")
>> Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
>> Acked-by: Marc Zyngier <maz@kernel.org>

[...]

> Ok, let's try this now.

   Well, better late than never! :-)

> Worst case, we revert it later :)

   Please just don't revert it outright on the 1st issue report -- give me time
to look at the issue(s) reported...
   BTW, I've CC'ed you on the SH patch that avoids using IRQ0. Please help to
merge it (v1/v2 were posted on February 11th and there was no motion since then)!

> thanks,
> 
> greg k-h

MBR, Sergey