linux-kernel - Re: [PATCH v2 1/1] Input: atmel_mxt_ts - Get IRQ edge/level flags on DT booting

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Message-ID: <CAD=FV=WSNqjHLLbTh1LBF3RFrCnWnj498hivivcmx1SbuYp=Hw@mail.gmail.com>
Date:	Fri, 8 Aug 2014 13:54:10 -0700
From:	Doug Anderson <dianders@...omium.org>
To:	Javier Martinez Canillas <javier.martinez@...labora.co.uk>
Cc:	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Nick Dyer <nick.dyer@...ev.co.uk>,
	Stephen Warren <swarren@...dia.com>,
	Yufeng Shen <miletus@...omium.org>,
	Benson Leung <bleung@...omium.org>,
	Olof Johansson <olof@...om.net>,
	Tomasz Figa <tomasz.figa@...il.com>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Jason Cooper <jason@...edaemon.net>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Abraham <thomas.ab@...sung.com>
Subject: Re: [PATCH v2 1/1] Input: atmel_mxt_ts - Get IRQ edge/level flags on
 DT booting

Hi,

On Fri, Aug 8, 2014 at 11:29 AM, Javier Martinez Canillas
<javier.martinez@...labora.co.uk> wrote:
> Hello,
>
> On 08/08/2014 06:38 PM, Javier Martinez Canillas wrote:
>>
>>
>> It seems as if the first call to exynos_irq_set_type() that is made by OF is a
>> no-op while the second call is the one that actually setups the hw correctly.
>> Does this make any sense? Maybe is related to the pin not being muxed in the
>> correct function when the "interrupts" property is parsed by OF?
>>
>
> So after a conversation with Tomasz Figa over IRC the problem was after all that
> the pin was reconfigured. The IRQ trigger type resulted to be just a red herring
> and not a direct cause.
>
> The pinctrl-eyxnos driver does the IRQ pinmux setup in the .irq_set_type
> function handler. So what happened was that OF parsed the "interrupts" property
> and called exynos_irq_set_type() which did the pinmux setup.
>
> But after that, due a DTS pinctrl configuration the pin function was changed as
> a GPIO input and that happened before the atmel driver was probed. So when the
> driver called request_threaded_irq(), the correct flags were used but the pin
> was not configured as an IRQ anymore so IRQ were not fired.
>
> Setting a trigger type just had the side effect of calling exynos_irq_set_type()
> which again setup the pin as an IRQ.
>
> To fix the issue a variation of patch [0] will be posted that moves the IRQ
> pinmux setup from .irq_set_type to the .irq_request_resources function handler.
> That way the pin will be setup as IRQ regardless of the the trigger type [1]
> when someone calls request_[threaded]_irq().
>
> Only the mentioned patch fixes the issue but Tomasz said that even a call to
> gpio_direction_{input,output} can change the pin configuration so he will post
> another patch that will add a bit mask to samsung_pin_bank to prevent any pinmux
> reconfiguration.

Would just making a device tree change fix this?  AKA for the pin, do:

  samsung,pin-function = <0xf>;

I have some vague recollection that I set interrupts to pin-function
"0" by default for some reason (assuming they would go to 0xf when
interrupts were enabled).  ...but I can't for the life of me remember
if it was a good reason or just seemed like the right thing to do.

-Doug
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