Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Arnd Bergmann]

On Thursday 13 November 2014 11:35:42 Alexander Stein wrote:
> On Wednesday 12 November 2014 20:16:06, Arnd Bergmann wrote:
> > On Wednesday 12 November 2014 17:38:31 Alexander Stein wrote:
> > > On Wednesday 12 November 2014 17:04:57, Arnd Bergmann wrote:
> > > > On Wednesday 12 November 2014 17:02:56 Alexander Stein wrote:
> > > > > This features already exists for board config setups. Add support for
> > > > > device tree based systems.
> > > > > 
> > > > > Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
> > > > > ---
> > > > > Please note: Due to current lack of hardware I could not test it yet. V2
> > > > > includes the changes proposed by Dmitry.
> > > > > 
> > > > > Changes in v2:
> > > > > * Added device tree bindings
> > > > > * IRQ is only parsed and mapped when there is no "gpios" property
> > > > > 
> > > > 
> > > > Can you list one or more examples in the patch description?
> > > > Are these systems that don't expose the GPIO controller with a
> > > > standalone driver, or systems that really actually connect the
> > > > buttons to an interrupt pin?
> > > 
> > > You mean a use case? I came to this situation to test interrupt polarity on a microcontroller, thus a simple /IRQ pin, no GPIO at all. So in the end I have an input just connected to an interrupt line.
> > > I noticed gpio_keys using platform data only can be used for this setup. So I added this support for device tree.
> > > 
> > 
> > I meant a specific board file that uses this, which can't be converted
> > to DT without your change.
> 
> I've searched (hopefully) the complete arch/ tree on v3.18-rc4 for
> struct gpio_keys_button and checked each occurrence. I didn't found
> any usage of IRQ based input keys.

Ok, I see.

I notice that Laxman Dewangan initially added the feature as part of
(I assume) work on Tegra, but these days Tegra is DT-only so it can't
actually get used for that any more.

If we have a real usecase, I think we can still take your patch, but
my impression at the moment is that it may be better to instead
remove the feature entirely by reverting d8ee4a1c9052 ("Input:
gpio_keys - add support for interrupt only keys").

Regarding your initial use case of testing interrupt polarity, would
you have been able to do the same thing by looking at the interrupt
count in /proc/interrupts?

	Arnd

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Alexander Stein]

On Thursday 13 November 2014 11:47:13, Arnd Bergmann wrote:
> Regarding your initial use case of testing interrupt polarity, would
> you have been able to do the same thing by looking at the interrupt
> count in /proc/interrupts?

This is only possible if some driver actually requests this interrupt, no?

Best regards,
Alexander
-- 
Dipl.-Inf. Alexander Stein

SYS TEC electronic GmbH
Am Windrad 2
08468 Heinsdorfergrund
Tel.: 03765 38600-1156
Fax: 03765 38600-4100
Email: alexander.stein@systec-electronic.com
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Managing Director: Dipl.-Phys. Siegmar Schmidt
Commercial registry: Amtsgericht Chemnitz, HRB 28082

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Laxman Dewangan]

On Thursday 13 November 2014 04:17 PM, Arnd Bergmann wrote:
> On Thursday 13 November 2014 11:35:42 Alexander Stein wrote:
>> On Wednesday 12 November 2014 20:16:06, Arnd Bergmann wrote:
>>> On Wednesday 12 November 2014 17:38:31 Alexander Stein wrote:
>>>> On Wednesday 12 November 2014 17:04:57, Arnd Bergmann wrote:
>>>>> On Wednesday 12 November 2014 17:02:56 Alexander Stein wrote:
>>>>>> This features already exists for board config setups. Add support for
>>>>>> device tree based systems.
>>>>>>
>>>>>> Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
>>>>>> ---
>>>>>> Please note: Due to current lack of hardware I could not test it yet. V2
>>>>>> includes the changes proposed by Dmitry.
>>>>>>
>>>>>> Changes in v2:
>>>>>> * Added device tree bindings
>>>>>> * IRQ is only parsed and mapped when there is no "gpios" property
>>>>>>
>>>>> Can you list one or more examples in the patch description?
>>>>> Are these systems that don't expose the GPIO controller with a
>>>>> standalone driver, or systems that really actually connect the
>>>>> buttons to an interrupt pin?
>>>> You mean a use case? I came to this situation to test interrupt polarity on a microcontroller, thus a simple /IRQ pin, no GPIO at all. So in the end I have an input just connected to an interrupt line.
>>>> I noticed gpio_keys using platform data only can be used for this setup. So I added this support for device tree.
>>>>
>>> I meant a specific board file that uses this, which can't be converted
>>> to DT without your change.
>> I've searched (hopefully) the complete arch/ tree on v3.18-rc4 for
>> struct gpio_keys_button and checked each occurrence. I didn't found
>> any usage of IRQ based input keys.
> Ok, I see.
>
> I notice that Laxman Dewangan initially added the feature as part of
> (I assume) work on Tegra, but these days Tegra is DT-only so it can't
> actually get used for that any more.
>
> If we have a real usecase, I think we can still take your patch, but
> my impression at the moment is that it may be better to instead
> remove the feature entirely by reverting d8ee4a1c9052 ("Input:
> gpio_keys - add support for interrupt only keys").
>
> Regarding your initial use case of testing interrupt polarity, would
> you have been able to do the same thing by looking at the interrupt
> count in /proc/interrupts?
>

Yes, I posted patch for interrupt key on context on key connected to 
PMIC-Onkey.
On PMIC, there is onkey pin input which generates interrupt only when it 
toggles. So if we have key (power key on our platforms) connected to 
this pin then we will only get interrupt from PMIC.
Instead of implementing full interrupt key driver, I added this support 
on existing gpio keys.

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Arnd Bergmann]

On Thursday 13 November 2014 11:52:48 Alexander Stein wrote:
> On Thursday 13 November 2014 11:47:13, Arnd Bergmann wrote:
> > Regarding your initial use case of testing interrupt polarity, would
> > you have been able to do the same thing by looking at the interrupt
> > count in /proc/interrupts?
> 
> This is only possible if some driver actually requests this interrupt, no?

Yes, I think that is correct, at least with sparseirq, which is now the
default. For interrupts that are mapped by the irqchip, you can look
up the number of spurious interrupts in /proc/irq/<nr>/spurious.

	Arnd

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Laxman Dewangan]

On Thursday 13 November 2014 04:30 PM, Arnd Bergmann wrote:
> On Thursday 13 November 2014 11:52:48 Alexander Stein wrote:
>> On Thursday 13 November 2014 11:47:13, Arnd Bergmann wrote:
>>> Regarding your initial use case of testing interrupt polarity, would
>>> you have been able to do the same thing by looking at the interrupt
>>> count in /proc/interrupts?
>> This is only possible if some driver actually requests this interrupt, no?
> Yes, I think that is correct, at least with sparseirq, which is now the
> default. For interrupts that are mapped by the irqchip, you can look
> up the number of spurious interrupts in /proc/irq/<nr>/spurious.
>
>
yes, I came across multiple PMIC(TPS65910, MAXIM, Ricoh)  module which 
generates interrupt when their On-key pin get toggle. Key is connected 
with this pin of PMIC and for on-key driver, we are using the gpio-keys 
driver by passing interrupt number instead of complete new driver.

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Arnd Bergmann]

On Thursday 13 November 2014 16:29:02 Laxman Dewangan wrote:
> On Thursday 13 November 2014 04:17 PM, Arnd Bergmann wrote:
> > I notice that Laxman Dewangan initially added the feature as part of
> > (I assume) work on Tegra, but these days Tegra is DT-only so it can't
> > actually get used for that any more.
> >
> > If we have a real usecase, I think we can still take your patch, but
> > my impression at the moment is that it may be better to instead
> > remove the feature entirely by reverting d8ee4a1c9052 ("Input:
> > gpio_keys - add support for interrupt only keys").
> >
> > Regarding your initial use case of testing interrupt polarity, would
> > you have been able to do the same thing by looking at the interrupt
> > count in /proc/interrupts?
> >
> 
> Yes, I posted patch for interrupt key on context on key connected to 
> PMIC-Onkey.
> On PMIC, there is onkey pin input which generates interrupt only when it 
> toggles. So if we have key (power key on our platforms) connected to 
> this pin then we will only get interrupt from PMIC.
> Instead of implementing full interrupt key driver, I added this support 
> on existing gpio keys.

So is this code still in place, and do you think it's worthwhile to
have a DT binding for it?

Could the PMIC register a gpio controller instead?

	Arnd

Re: [PATCH v2 1/1] Input: gpio_keys - add device tree support for interrupt only keys

[Laxman Dewangan]

On Thursday 13 November 2014 04:35 PM, Arnd Bergmann wrote:
> On Thursday 13 November 2014 16:29:02 Laxman Dewangan wrote:
>>
>> Yes, I posted patch for interrupt key on context on key connected to
>> PMIC-Onkey.
>> On PMIC, there is onkey pin input which generates interrupt only when it
>> toggles. So if we have key (power key on our platforms) connected to
>> this pin then we will only get interrupt from PMIC.
>> Instead of implementing full interrupt key driver, I added this support
>> on existing gpio keys.
> So is this code still in place, and do you think it's worthwhile to
> have a DT binding for it?
>
> Could the PMIC register a gpio controller instead?
>
>

This pin is not supported as GPIO and so exporting the functionality 
through GPIO is not feasible until we treat the onkey as GPIO pin 
without actual gpio functionality i..e only interrupt functionality.