jamess-huang
commented
5 years ago The group of GPIO5 has the below 32 pins. GPIO5 A0 ~ GPIO5 A7, GPIO5 B0 ~ GPIO5 B7, GPIO5 C0 ~ GPIO5 C7, GPIO5 D0 ~ GPIO5 D7 and you can use the below rule to map to the dts settings GPIOx A0 -> 0 GPIOx A1 -> 1 GPIOx A2 -> 2 … GPIOx A7 -> 7 GPIOx B0 -> 8 GPIOx B1 -> 9 GPIOx B2 -> 10 ... GPIOx B7 -> 15 GPIOx C0 -> 16 GPIOx C1 -> 17 GPIOx C2 -> 18 GPIOx C3 -> 19
So as you can see, the <&gpio5 19 0> is mapping to GPIO5 C3.
Then please look up the below picture, you can find that the GPIO5C3 is mappping to physical pin 22.
Also is is possible to override this.
Where is the documentation which maps the physical pins onto the chip pin specification inside the overlays, i.e:
gpios = <&gpio5 19 0>;
the &gpio5 19 presumably maps to a physical pin - is there a mapping documented somewhere?
The overlay is here: https://github.com/TinkerBoard/debian_kernel/blob/2e432c3bcf918e83605970830b85d4695aff82fa/arch/arm/boot/dts/overlays/pps-gpio-overlay.dts