colibri PXA320 and UCB1400 - touch screen troubles

Daniel Mack daniel at caiaq.de
Wed Aug 11 06:02:10 EDT 2010


You dropped all recipients again and only replied to me.
PLEASE DON'T DO THAT.
Always keep all people in the loop, always.

On Wed, Aug 11, 2010 at 01:50:43PM +0400, Yuri Ludkevich wrote:
> 2010/8/11 Daniel Mack <daniel at caiaq.de>
> > According to my reverse engineering, this should be GPIO4_2.
> >
> 
> Thanks a lot.
> 
> BTW: does /sys/class/gpio/export support GPIOX_2 pins?

Yes, they are aliases to the signals without the "_2" suffix. Quoting
the PXA reference manual, chapter 5.3:

GPIO<6_0>_2:

General-Purpose IO Ports, second instantiation. The same signals as
GPIO<6:0>, but they are given separate names because they are configured
on separate multi-function pins. The recommended configuration is for
both multi-function pin instantiations of these GPIOs not to be
configured simultaneously for GPIO functionality. The preferred
configuration for dual instantiation GPIO usage (that is, using both
GPIO<6:0> and GPIO<6:0>_2 functions) is to configure one multi-function
pin as a GPIO and the second multi-function pin instantiation for an
alternate function other than a GPIO function. Configuring GPIO<6:0> to
be present on two separate multi-function pins is not recommended.
However, when GPIO<6:0> is configured as an output and both
multi-function pin instantiations are programmed for GPIO function, the
primary and secondary instantiation of the multi-function pins are both
outputs from the common GGPIO<6:0> signal. However, when GPIO<6:0> is an
input, the inputs from both multi-function pin instantiations are ORed
together before the result is sent to the internal GPIO<6:0> input
logic.


HTH,
Daniel




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