I wrote: > For simplicity, I use > the "gpio" cable driver, which accesses GPIOs through > /sys/class/gpio/...
One issue with this approach is that allocation of GPIOs can outlive the process making the allocation. UrJTAG cleans up when exiting normally but doesn't when killed by a signal. This doesn't trouble later runs of UrJTAG or any of the other user-space utilities that use the 8:10 interface, but if trying to load a kernel driver after UrJTAG has quit messily, the driver will fail to allocate its GPIOs. E.g., # echo jz4740-mmc.0 >/sys/bus/platform/drivers/jz4740-mmc/bind ash: write error: No such device dmesg reveals what happened: jz4740-mmc jz4740-mmc.0: Failed to request mmc pins: -16 jz4740-mmc: probe of jz4740-mmc.0 failed with error -16 To clean up after UrJTAG, run # ls -1 /sys/class/gpio/ | sed -n s/gpio1/1/p | while read n; do echo $n >/sys/class/gpio/unexport; done or, more specific for n in 105 107 108 109; do echo $n >/sys/class/gpio/unexport; done By the way, the numbers are calculated from the port base plus the pin number. For example, UBB-JTAG-M1 puts TMS on DAT2. DAT2 is pin 12 of port D. The base of the port is 4*32 = 96 and the GPIO number is thus 96+12 = 108. - Werner _______________________________________________ Qi Hardware Discussion List Mail to list (members only): [email protected] Subscribe or Unsubscribe: http://lists.en.qi-hardware.com/mailman/listinfo/discussion
