gpio_keys and how PXA27x sets gpio_set_wake() (was Re: sharp c-3000 aka spitz: fix warn_on introduced in 2.6.32-rc1)

[Eric Miao]

2010/1/26 Stanislav Brabec <utx at penguin.cz>:
> Eric Miao wrota:
>
>> I prefer 2) - the ugly and hardcoded setup in spitz_pm.c should really
>> be removed. That's why the gpio_set_wake() and keypad_set_wake()
>> are introduced.
>
> I am unsure, whether gpio_keys driver is interested in the way, how wake
> happens. I guess that is interested only in the fact, that wake
> happened.
>
> Handling platform specific edge/level wake setup would only complicate
> the code. (In fact, even the PXA270 platform code does not exist yet -
> arch/arm/mach-pxa/mfp-pxa2xx.c:__mfp_config_gpio() is not capable to
> configure Power Manager Keyboard Wake-Up Enable Register (PKWR).)
>

That's why WAKEUP_ON_EDGE_* is introduced, no need for gpio-keys
to know this.

> I talked to Vojtěch Pavlík and he told that 1 is correct: Follow
> include/linux/interrupt.h. Setting edge/level wake mode should be done
> in the platform file. The driver could use just irq_set_wake() and don't
> care about details. And irq_set_wake() should do something useful even
> for PKWR capable GPIO.
>

I don't mind if IRQF_TRIGGER_ will always be correct regarding the
wakeup edge/level settings in MFP, but honestly - I don't think so.

>> keypad_set_wake() is really specifically introduced for use by pxa27x_keypad
>> and no generic GPIO stuffs. So it's really annoying a GPIO will use
>> the PKWR as a wakeup GPIO, I'd recommend one still get this hard coded
>> into the platform file, with combination of WAKEUP_ON_LEVEL_HIGH (which
>> is specifically designed for keypad GPIOs) and keypad_set_wake().
>
> Well, keypad_set_wake() seems to be possibly broken for GPIO 38. Imagine
> a device, that has a small keypad, but GPIO 38 has a different purpose
> that requires an edge triggered wakeup (PWER). I think that
> keypad_set_wake() reprograms it to PKWR.

Unless someone specifies that by

GPIO38_GPIO | WAKEUP_ON_LEVEL_HIGH,

keypad_set_wake() will never try to enable the bit in PKWR.

>
> The problem affects gpio_keys: It is a driver implementing "one key per
> gpio". It now handles On/Off and lid switches on Zaurus. Lid switches
> are on "normal" GPIOs, On/Off switch is wired to PKWR capable GPIO.
>

Ain't On/Off switch one of the matrix key? And so SPITZ_GPIO_KEY_INT
could be used to handle that?

>> The spitz, however, is doing a good job on this though it's using a GPIO
>> emulated matrix keypad, that there is a separate SPITZ_GPIO_KEY_INT,
>> which triggers whenever there is any key press on this matrix (I don't
>> know how that's designed in HW, but it seems to do that job), and
>> which can be setup as a GPIO wakeup.
>
> SPITZ_GPIO_KEY_INT happens if AC adapter is connected or key is pressed.
> Surprisingly, the key press logic is part of NAND flash controller CPLD.
> SPITZ_GPIO_KEY_INT==0 - it makes possible to wake Zaurus even from deep
> sleep by any key press. It would be impossible only with PKWR.
>
> I guess that this and implementation of keypad_set_wake() is a reason,
> why most devices suspend and resume correctly even if the irq_set_wake()
> refuses to configure wake and the warning is only visible symptom.