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

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Message-ID: <20180302114909.u6kqdszt3aew2io2@mwanda>
Date:   Fri, 2 Mar 2018 14:49:09 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Russell King - ARM Linux <linux@...linux.org.uk>
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        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>
Subject: Re: [PATCH] i2c: s3c2410: Properly handle interrupts of number 0

On Fri, Mar 02, 2018 at 11:19:31AM +0000, Russell King - ARM Linux wrote:
> 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.
> 

Those patches to make platform_get_irq() return error codes were merged
12 years ago in commit 305b3228f9ff ("[PATCH] driver core:
platform_get_irq*(): return -ENXIO on error").

This patch just drops the check for zero which is should be fine.

regards,
dan carpenter