linux-kernel - Re: [PATCH V7 1/1] drivers/gpio: Altera soft IP GPIO driver and devicetree binding

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Date:	Mon, 21 Apr 2014 02:21:11 +0000
From:	Tien Hock Loh <thloh@...era.com>
To:	Josh Cartwright <joshc@...eaurora.org>
CC:	Dinh Nguyen <dinguyen@...era.com>, Ley Foon Tan <lftan@...era.com>,
	"robh+dt@...nel.org" <robh+dt@...nel.org>,
	"pawel.moll@....com" <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Rob Landley <rob@...dley.net>,
	Linus Walleij <linus.walleij@...aro.org>,
	Alexandre Courbot <gnurou@...il.com>,
	"Grant Likely" <grant.likely@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"thloh.linux@...il.com" <thloh.linux@...il.com>
Subject: Re: [PATCH V7 1/1] drivers/gpio: Altera soft IP GPIO driver and
 devicetree binding

On Isn, 2014-04-07 at 12:11 -0500, Josh Cartwright wrote:
> On Mon, Apr 07, 2014 at 04:00:43PM +0800, Tien Hock Loh wrote:
> > On Wed, Mar 19, 2014 at 6:09 PM, Tien Hock Loh <thloh@...era.com> wrote:
> > > On Fri, Mar 7, 2014 at 11:14 PM, Josh Cartwright <joshc@...eaurora.org> wrote:
> > >> On Mon, Mar 03, 2014 at 06:27:43PM +0800, thloh@...era.com wrote:
> > >>> From: Tien Hock Loh <thloh@...era.com>
> [..]
> > >>> +     altera_gc->mapped_irq = irq_of_parse_and_map(node, 0);
> > >>>
> > >>
> > >> platform_get_irq(pdev, 0);
> > >>
> > > OK.
> > >
> >
> > platform_get_irq doesn't create the irq mapping which is needed by the
> > driver. Since this driver is targeted at using of, should I be using
> > irq_of_parse_and_map or should I still redo the codes with
> > platform_get_irq and irq_create_mapping? I think the latter would be
> > introducing code redundancy. Please advice.
>
> Yes, it is technically true that platform_get_irq() doesn't do the
> mapping directly, but that's because the mapping is setup earlier, when
> of_device_alloc() (drivers/of/platform.c) allocates resources for your
> platform device.
>
> Calling irq_of_parse_and_map() should be unnecessary.

I checked and tried running the without irq_create_mapping but it seems
the mapping is not done. What I've seen other GPIO driver is doing is to
create the mapping during the gpio_to_irq call. However Linus suggested
we are avoiding that route, thus the use of irq_of_parse_and_map.

Do you agree with my findings?

>


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