On Fri, Oct 09, 2015 at 11:45:17AM +0200, Rolf Peukert wrote:
> On 09.10.2015 02:54, Ladislav Michl wrote:
> > Hi there!
> >
> > on custom AM37x board running 2.6.37 this was enough to enable gpio 67:
> > echo 71 > /sys/class/gpio/export
> > echo out > /sys/class/gpio/gpio71/direction
> > echo 1 > /sys/class/gpio/gpio71/value
> >
> > However, with DT configured linux-4.2 compiled using omap2plus_defconfig
> > this no longer works.
> [...]
>
> Is some other device driver using these pins? Pins 70 and 71 could be
> DSS or UART1. Maybe you need to set them to "disabled" in your DT.
Only UART2 is enabled. This should not make difference anyway, as it should
be matter of mux config and gpio settings. Working GPIO 82 is on the same
bank as GPIO 71 and to make it work from U-Boot only these registers need
to be touched:
=> mw.l 0x480020DC 0x40004
=> mw.l 0x480020F4 0x40004
=> mw.l 0x49052034 0xFFF41F3F
=> mw.l 0x4905203C <value>
First two writes are mux config, 3rd is direction and the last one is output.
Both GPIO 71 and 82 could be driven this way. But as long as kernel steps in,
GPIO 71 no longer works even if I use devmem utility to write relevant
registers. Just tried 3.19.8 and it does not work either, moving backward
to the past...
Regards,
ladis
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