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

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Date:	Wed, 6 Aug 2014 23:09:26 -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 03:47:24AM +0200, Javier Martinez Canillas wrote:
> Hello Tomasz,
> 
> Thanks a lot for your feedback.
> 
> On 08/07/2014 03:14 AM, Tomasz Figa wrote:
> > Hi Javier,
> > 
> > 
> > Have you observed an actual failure due to this? I believe that
> 
> Yes, I found this issue since the driver was not taking into account the value
> defined in the edge/level type cells from the "interrupts" DT property.
> 
> Only doing the change in the following patch was not enough:
> 
> [PATCH 1/1] ARM: dts: Add Peach Pit and Pi dts entry for atmel touchpad [0].
> 
> > 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.

> 
> >>  
> >> +	if (client->dev.of_node)
> >> +		irqflags = irq_get_trigger_type(client->irq);
> > 
> > It might be a bit cleaner to just assign the flags to pdata->irqflags in
> > mxt_parse_dt() instead. That would also account for the fact that pdata,
> > if provided, should have priority over DT.
> > 
> 
> You are totally right, also this will break if CONFIG_OF is not enabled since
> dev.of_node will not be defined. While this already is taken into account for
> mxt_parse_dt() by defining an empty function.
> 
> I'll change it in v2 if getting the flags from the driver is the right approach

Yes, please.

> instead of fixing the irqchip driver or the IRQ core.

Thanks.

-- 
Dmitry
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