[PATCH 2/5] ARM: PXA: Zipit Z2: Add USB host and device support

[Vasily Khoruzhick]

On Wed, Oct 31, 2012 at 6:31 PM, Haojian Zhuang
<haojian.zhuang at gmail.com> wrote:
> On Wed, Oct 31, 2012 at 4:05 AM, Daniel Mack <zonque at gmail.com> wrote:
>>
>> On 30.10.2012 21:01, Vasily Khoruzhick wrote:
>> > On Mon, Oct 29, 2012 at 2:14 PM, Daniel Mack <zonque at gmail.com> wrote:
>> >> On 29.10.2012 12:12, Vasily Khoruzhick wrote:
>> >>> On Mon, Oct 29, 2012 at 2:00 PM, Daniel Mack <zonque at gmail.com> wrote:
>> >>>
>> >>>>> Well, there's an issue - Z2 does not preserve memory contents in deep sleep
>> >>>>> (but it does in sleep), so userspace can't be fixed here unfortunatelly.
>> >>>>> There's no another possibility to turn Z2 off, and plain sleep is too
>> >>>>> power hungry.
>> >>>>> So the only way to keep Z2 in low-power mode is fake power off, which just puts
>> >>>>> Z2 in deep sleep.
>> >>>>
>> >>>> Why can't the userspace trigger a deep sleep then instead of powering
>> >>>> off? Which details do I lack?
>> >>>
>> >>> How? echo mem >/sys/power/state puts system into non-deep sleep. Anyway, kernel
>> >>> is not ready for fake power off instead of suspend (we can't resume
>> >>> from deep sleep,
>> >>> memory content is not preserved), so there can be some data loss.
>> >>> Adding some sysfs file to control sleep type does not look like a good
>> >>> idea to me.
>> >>>
>> >>> Btw, how other DT-capable boards handle power off?
>> >>
>> >> No idea. I never actually used that kind of power state.
>> >
>> > Hi Daniel,
>> >
>> > One more question: what should I use instead of pxa2xx_mfp_config in
>> > DT board to configure pin modes?
>>
>> Haojian was working on the PXA pinctrl drivers, but I don't know how far
>> that is yet.
>>
>> If that's not yet there, have a look at the pinctrl-single driver. It's
>> admittedly not as nice to use as the constants in the board file as DT
>> lacks defines for numerical constants, but's at least a workaround.
>>
>> On a more general note, it's arguable whether this kind of setup should
>> be done in the bootloader after all.
>>
>>
>> Daniel
>>
>
> I prefer to use pinctrl-single driver instead. I'm updating mmp
> pinctrol driver to
> pinctrl-single driver framework. You can find them in mailist. I'm submitting
> a third round in these days.
>
> Regards
> Haojian

OK, one more question:

On PXA2xx GPIO and PINMUX are not separate blocks. Each pin can be
either input or output and have 4 modes (gpio + 3 alternate functions)
== 8 states , so we have: gpio in, gpio out, 3 alt in, 3 alt out.
To control pin mode one should write to GPDR (direction register) and
GAFR (alternate function register). pxa-gpio driver controls both of
those registers, so does pxa2xx-mfp.

I'm not sure what to do in this case. Should I move code controlling
GPDR and GAFR into some pinctrl-pxa2xx driver, and modify pxa-gpio
driver to use it?

Regards
Vasily