[RFC] edt-ft5x06 - cannot see IRQ Qfrom device after DT probe

[RFC] edt-ft5x06 - cannot see IRQ Qfrom device after DT probe

[Markus Niebel]

Hallo,

working with said tochcontroller we found that the IRQ is not seen in the following scenario:

- bootloader uses pin as an output for some reason 
- pin is configured as GPIO and as INT source via device tree
- driver loads correctly and communicates over I2C
- IRQs not seen by CPU becaus pin is still configured as output

- when adding an int-gpios node to devicetree and parsing this gpio the gpio will be configured as input
- IRQ can be seen by CPU

Question:

- shall we add an int-gpio property to enable gpio pin config as input or

Regards

Markus Niebel

Re: [RFC] edt-ft5x06 - cannot see IRQ Qfrom device after DT probe

[Simon Budig]

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On 15/07/14 19:43, Markus Niebel wrote:
> - when adding an int-gpios node to devicetree and parsing this gpio the gpio will be configured as input
> - IRQ can be seen by CPU
> 
> Question:
> 
> - shall we add an int-gpio property to enable gpio pin config as input or

Shouldn't it be possible to configure the pin as input directly from the
device tree, indepently from the touch driver section?

Bye,
        Simon

-- 
       Simon Budig                        kernel concepts GmbH
       simon.budig@kernelconcepts.de      Sieghuetter Hauptweg 48
       +49-271-771091-17                  D-57072 Siegen



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Re: [RFC] edt-ft5x06 - cannot see IRQ Qfrom device after DT probe

[Markus Niebel]

Am 16.07.2014 12:01, wrote Simon Budig:
> On 15/07/14 19:43, Markus Niebel wrote:
>> - when adding an int-gpios node to devicetree and parsing this gpio the gpio will be configured as input
>> - IRQ can be seen by CPU
>>
>> Question:
>>
>> - shall we add an int-gpio property to enable gpio pin config as input or
> 
> Shouldn't it be possible to configure the pin as input directly from the
> device tree, indepently from the touch driver section?

I don't see, how to do that, maybe I did miss the right point.

I digged through the gpio code. There are drivers (gpio-omap) that make sure, that gpio is configured as
input and others that don't care (gpio-mxc / gpio-mxs).

seeing this I posted "gpio: gpio-mxc: make sure gpio is input when request IRQ" on linux-arm-kernel

Global question is: how can we make sure, that the driver that request the IRQ requests also the GPIO (implicit or like in the old platfrom data days explicit)? But thats beyond input devices and my knowledge. 

Regards

Markus

> 
> Bye,
>         Simon
> 

Re: [RFC] edt-ft5x06 - cannot see IRQ Qfrom device after DT probe

[Simon Budig]

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On 22/07/14 12:40, Markus Niebel wrote:
> Am 16.07.2014 12:01, wrote Simon Budig:
>> On 15/07/14 19:43, Markus Niebel wrote:
>>> - when adding an int-gpios node to devicetree and parsing this 
>>> gpio the gpio will be configured as input - IRQ can be seen by 
>>> CPU
>>> 
>>> Question:
>>> 
>>> - shall we add an int-gpio property to enable gpio pin config as 
>>> input or
>> 
>> Shouldn't it be possible to configure the pin as input directly 
>> from the device tree, indepently from the touch driver section?
> 
> I don't see, how to do that, maybe I did miss the right point.

Try looking at

Documentation/devicetree/bindings/pinctrl/pinctrl-bindings.txt

There you have the "input-enable" generic property.

> Global question is: how can we make sure, that the driver that 
> request the IRQ requests also the GPIO (implicit or like in the old 
> platfrom data days explicit)? But thats beyond input devices and my 
> knowledge.

The driver does not depend on the IRQ coming from a "real" CPU gpio. It
*could* be an external gpio expander or whatever (whether that is a good
idea is debatable of course). When I submitted the first version of the
driver it had bits in it to configure the pin properly. The feedback
basically was to remove that, because it made some assumptions that you
can map the IRQ to the relevant GPIO, which is not always possible.

I hope that helps.

(But really, your bootloader really should have a *very* good reason to
configure the touch irq pin as output - I have the impression that right
now there are two outputs driving against each other in your setup - not
healthy for the hardware).

Bye,
        Simon

-- 
       Simon Budig                        kernel concepts GmbH
       simon.budig@kernelconcepts.de      Sieghuetter Hauptweg 48
       +49-271-771091-17                  D-57072 Siegen


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