linux-kernel - Re: [PATCH] i2c: s3c2410: Properly handle interrupts of number 0

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Message-ID: <20180302111931.GX9418@n2100.armlinux.org.uk>
Date:   Fri, 2 Mar 2018 11:19:31 +0000
From:   Russell King - ARM Linux <linux@...linux.org.uk>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     Kukjin Kim <kgene@...nel.org>, Wolfram Sang <wsa@...-dreams.de>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Ben Dooks <ben-linux@...ff.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH] i2c: s3c2410: Properly handle interrupts of number 0

On Thu, Mar 01, 2018 at 09:34:44PM +0100, Krzysztof Kozlowski wrote:
> Interrupt number 0 (returned by platform_get_irq()) might be a valid IRQ
> so do not treat it as an error.  If interrupt 0 was configured, the driver
> would exit the probe early, before finishing initialization, but with
> 0-exit status.

The official position (as stated by Linus) is that interrupt zero is
not a valid interrupt for peripheral drivers (it may be valid within
architecture code for things like the x86 PIT, but nothing else.)

You need to number your platform interrupts from one rather than zero.

Note that there have been patches proposed to make platform_get_irq()
return an error rather than returning a value of zero, so changing
the driver in this way is not a good idea.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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