Re: GPIO request failure with PCF pinmux

[Paul Mundt <lethal@linux-sh.org>]

On Fri, Sep 14, 2012 at 10:36:34PM +0200, Laurent Pinchart wrote:
> And while I'm at it, trying to set the pin to the PWM function doesn't seem to 
> work anymore on v3.6. It looks like the pin stays configured as a GPIO. How am 
> I supposed to configure pinmuxing from the driver ? Documentation/pinctrl.txt 
> doesn't help much, and the code isn't easy to understand. There's probably no 
> registered mapping (whatever a mapping is), are they supposed to come from DT 
> ?

For the moment requesting as a function as before should be fine,
although it's possible that your config-as-gpio reconfig-as-function flow
has tripped up some of the logic. Both were tested independently, but as
you can tell I've overlooked the reuse of the same pin by the same driver
in different ways case.

And yes, you've hit on the next phase of the pfc rework. At present we
have a GPIO shim that enables function requests via the GPIO API as
before, but it's not the way we want to go forward and remains there only
for backwards compatability.

More work needs to be done both in the drivers and the board/platform to
make use of pinctrl mappings. I have some work in progress for sh-sci,
but ran out of time to get it merged for this merge window.

The DT support is something else that has to be worked out. I personally
have no interest in supporting DT, as I view the entire endeavour as
nothing but a solution in search of a problem. If someone wants DT
support for this they're welcome to hack something up, though. I won't
oppose DT changes going in, regardless of whether they're ultimately a
waste of time or not.