linux-kernel - Re: [RFC] gpio/omap: auto-setup a GPIO when used as an IRQ

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Message-ID: <524089DF.600@ti.com>
Date:	Mon, 23 Sep 2013 14:35:11 -0400
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>,
	Linus Walleij <linus.walleij@...aro.org>,
	Grant Likely <grant.likely@...aro.org>
CC:	Tony Lindgren <tony@...mide.com>,
	Kevin Hilman <khilman@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Lars Poeschel <larsi@....tu-dresden.de>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ian.campbell@...rix.com>,
	Kumar Gala <galak@...eaurora.org>,
	Pawel Moll <pawel.moll@....com>,
	Tomasz Figa <tomasz.figa@...il.com>,
	Enric Balletbo i Serra <eballetbo@...il.com>,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>,
	Balaji T K <balajitk@...com>,
	Jon Hunter <jgchunter@...il.com>, <linux-gpio@...r.kernel.org>,
	<linux-omap@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [RFC] gpio/omap: auto-setup a GPIO when used as an IRQ

Javier,

On Monday 23 September 2013 01:07 PM, Tony Lindgren wrote:
> * Javier Martinez Canillas <javier.martinez@...labora.co.uk> [130923 10:09]:
>> On 09/23/2013 06:45 PM, Tony Lindgren wrote:
>>>
>>> Hmm does this still work for legacy platform data based
>>> drivers that are doing gpio_request() first?
>>>
>>
>> Yes it still work when booting using board files. I tested on my OMAP3 board and
>> it worked in both DT and legacy booting mode.
> 
> OK great.
>  
>>> And what's the path for clearing things for PM when free_irq()
>>> gets called? It seems that this would leave the GPIO bank
>>> enabled causing a PM regression?
>>>
>>
>> Indeed, I did set bank->mod_usage |= 1 << offset so the bank is enabled if the
>> device goes to suspended and then resumed but I completely forget about the
>> clearing path when the IRQ is freed.
>>
>> Which makes me think that we should probably maintain two usage variables, one
>> for GPIO and another one for IRQ and check both of them on the suspend/resume pm
>> functions.
> 
> Yes that it seems that they should be treated separately.
> 
As discussed on IRC, the patch as such is fine after the mentioned fixup,
I would like to hear back if Linus W/Grant is fine with the approach. Not sure
if I missed the discussion, but the proposed patch is deviation from
traditional method of doing gpio_request() first up to perform other
gpio operations.

Regards,
Santosh


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