linux-kernel - Re: [PATCH 1/2] Input: atmel_mxt_ts - Get IRQ edge/level flags on DT booting

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Date:	Thu, 7 Aug 2014 09:47:25 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Tomasz Figa <tomasz.figa@...il.com>,
	Nick Dyer <nick.dyer@...ev.co.uk>,
	Stephen Warren <swarren@...dia.com>,
	Yufeng Shen <miletus@...omium.org>,
	Benson Leung <bleung@...omium.org>,
	Doug Anderson <dianders@...omium.org>,
	Olof Johansson <olof@...om.net>, linux-input@...r.kernel.org,
	devicetree@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] Input: atmel_mxt_ts - Get IRQ edge/level flags on DT
 booting

On Thu, Aug 07, 2014 at 09:49:49AM +0200, Javier Martinez Canillas wrote:
> Hello Dmitry,
> 
> On 08/07/2014 08:09 AM, Dmitry Torokhov wrote:
> >> 
> >> > irq_of_parse_and_map() already sets up IRQ trigger type based on DT
> >> > data, by calling irq_create_of_mapping() which in turn calls
> >> > irq_set_irq_type().
> >> >
> >> 
> >> Right but somehow when the IRQ is actually requested the type is overwritten by
> >> the value passed to request_threaded_irq() and interrupts are not being
> >> generated by the device without this patch.
> >> 
> >> Do you think that this is a bug in the "interrupt-parent" irqchip driver or the
> >> IRQ core? I'm not that familiar with the IRQ subsystem.
> > 
> > No, this is clearly driver fault - it smashed previously done setup with new
> > flags.
> >
> 
> Thanks a lot for the clarification. That was my understanding as well but wanted
> to be sure.

Actually, I take this back. In mainline everything as it should: if
pdata does not specify particular trigger the flags requested end up
being IRQF_ONESHOT, which should preserve trigger bits previously set up
by the board or OF code. In Chrome kernel we have:

	/* Default to falling edge if no platform data provided */
	irqflags = data->pdata ? data->pdata->irqflags : IRQF_TRIGGER_FALLING;
	error = request_threaded_irq(client->irq, NULL, mxt_interrupt,
				     irqflags | IRQF_ONESHOT,
				     client->name, data);

which I believe should go away. If it is needed on ACPI systems we need
to figure out how to do things we can do with OF there.

Thanks.

-- 
Dmitry
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