linux-kernel - Re: [PATCH v2 1/4] MFD: Palmas: Check if interrupts property exists and then only request irq

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Date:	Tue, 18 Jun 2013 11:08:15 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	"J, KEERTHY" <j-keerthy@...com>
CC:	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	"broonie@...nel.org" <broonie@...nel.org>,
	"ldewangan@...dia.com" <ldewangan@...dia.com>,
	"sameo@...ux.intel.com" <sameo@...ux.intel.com>,
	"grant.likely@...retlab.ca" <grant.likely@...retlab.ca>,
	"swarren@...dia.com" <swarren@...dia.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"gg@...mlogic.co.uk" <gg@...mlogic.co.uk>
Subject: Re: [PATCH v2 1/4] MFD: Palmas: Check if interrupts property exists
 and then only request irq

On 06/18/2013 10:54 AM, J, KEERTHY wrote:
> Hi Stephen,
> 
>> -----Original Message-----
>> From: Stephen Warren [mailto:swarren@...dotorg.org]
>> Sent: Tuesday, June 18, 2013 9:22 PM
>> To: J, KEERTHY
>> Cc: linux-omap@...r.kernel.org; broonie@...nel.org;
>> ldewangan@...dia.com; sameo@...ux.intel.com; grant.likely@...retlab.ca;
>> swarren@...dia.com; linux-kernel@...r.kernel.org; linux-
>> doc@...r.kernel.org; gg@...mlogic.co.uk
>> Subject: Re: [PATCH v2 1/4] MFD: Palmas: Check if interrupts property
>> exists and then only request irq
>>
>> On 06/18/2013 04:01 AM, J Keerthy wrote:
>>> Check if interrupts property exists and then only request irq.
>>> On some boards INT line might not be connected to a valid irq line on
>>> the application processor. Hence keeping a check before requesting
>>> irq.
>>
>> When there is no interrupts property, surely i2c->irq == 0, which is an
>> invalid IRQ, and hence there's no need to check this before copying the
>> value?
> 
> The intent here is NOT to request irq with 0 or Invalid IRQ.

Sure.

> The board File will not populate the interrupts entry if the INT line is not
> Connected.

Do you mean the interrupts DT property won't be present if there is no
interrupt. If so, sure.

> Hence the patch checks for the 'interrupts' property.

That shouldn't be necessary; IIRC, the I2C core has already parsed the
interrupts property if there was one, and if there wasn't, it has set
i2c->irq to some invalid value already.

So, you simply need to check the value in i2c->irq, and don't need to
look at the DT at all.
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