External GPIO Chip not present iMX8MP android

[bradoconnell]

I am attempting to use the external gpio header (gpiochip5) on the iMX8MP-EVK running android but the device does not appear to be loaded. On debian (built with flexbuild) this chip is loaded fine and can be controlled with "gpioset gpiochip5" type commands but on the android build the device /dev/gpiochip5 is never created. This issue is present both in the stock android build and after ensuring that CONFIG_GPIO_PCA953X=y and CONFIG_GPIO_PCA953X_IRQ=y are set, that gpio-pca953x.o is built during the kernel build, and then re-flashing the boot and vendor_boot partitions.

[danielchen]

Hi @bradoconnell 

Maybe this is a sequence issue.   in my side , it start from gpiochip0

GPIO1 to GPIO5 listed as gpiochip0 to gpiochip4.

Regards

Daniel

[bradoconnell · Accepted solution]

No, those aren't the ones I'm referring to. /dev/gpiochip5 is created for the external gpio header by the pca953x driver (which I believe connects to a tca6416 chip on the EVK, but that I'm not certain of).

My kernel is working now to correctly create that device as shown below so this is fixed. I think what fixed my build was a full "make clean" before rebuilding the kernel (still with CONFIG_GPIO_PCA953X=y and CONFIG_GPIO_PCA953X_IRQ=y in imx8mp_gki.fragment)

[danielchen]

thanks for sharing.