GPIO commands on OMAP4

[Sascha Hauer]

On Thu, Apr 05, 2012 at 04:58:37PM +0200, Patrick wrote:
> On 04/05/2012 04:38 PM, Patrick wrote:
> >On 04/05/2012 03:49 PM, Sascha Hauer wrote:
> >>On Thu, Apr 05, 2012 at 11:40:49AM +0200, Patrick wrote:
> >>>Dear mailing-list,
> >>>
> >>>I am using a pcm049 phyCORE omap4430 module from Phytec with BareBox
> >>>2011.09.0 patched with BSP from Phytec.
> >>>
> >>>I would like to use the GPIO command to read a switch at startup.
> >>>This chip is connected on ABE_MCBSP1_DX (gpio_116). I have edited
> >>>the boards/pcm049/mux.c files to change the configuration of this
> >>>GPIO as follow: {ABE_MCBSP1_DX, (DIS | IEN | M3)} instead of
> >>>{ABE_MCBSP1_DX, (SAFE_MODE)}.
> >>>
> >>>I then use the "gpio_get_value 116" command followed by "echo $?" to
> >>>read the value. I always read a 0. On Linux I could read the right
> >>>value depending of the position of the switch, so it's not an
> >>>hardware problems.
> >>>
> >>>I have tried with one of the two LEDs on the module (gpio_152) and I
> >>>could change the LED state and read it back with gpio_get_value.
> >>>
> >>>I do not understand what I am doing wrong. Any help will be appreciated.
> >>
> >>What you tried should work. The only thing I can imagine is that you
> >>need a gpio_direction_input before reading the value.
> >>
> >>Sascha
> >>
> >I have found the the problem come from the mux configuration.
> >
> >I have added a call to set_muxconf_regs() from the gpio_get_value()
> >(this is only to try) and then it works. I have checked my configuration
> >and the lowlevel init is enabled:
> >
> >CONFIG_MACH_HAS_LOWLEVEL_INIT=y
> >CONFIG_MACH_DO_LOWLEVEL_INIT=y
> >
> >I am runnig my development version of barebox from the stable barebox
> >flashed on NAND. I do the following:
> >
> >tftp barebox.bin /dev/ram0
> >go /dev/ram0
> >
> >Could this be a problem ?

The mux config is executed from lowlevel_init which returns immediately
when it detects that barebox runs from SDRAM. So yes, that's your
problem.

Sascha


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