Hi all,
We have been using a custom board designed for iMX6 UL processor and we recently decided to switch to ULL processor on the same board. There wasn't any trouble with the transition. Now however, I've noticed this issue and can't seem to solve it.
We are using some SNVS_TAMPER pads as GPIO configured as outputs. In addition, we are reading the actual values on those output pins. I'm aware that SION bit is needed to be activated for that purpose. It works correctly with UL processor, but not with ULL processor it seems.
Below is the device-tree configuration of those pins for ULL processor:
&iomuxc_snvs {
pinctrl-names = "default_snvs";
pinctrl-0 = <&pinctrl_gpios_2>;
imx6ul-evk {
pinctrl_gpios_2: gpiosgrp-2 {
fsl,pins = <
MX6ULL_PAD_SNVS_TAMPER5__GPIO5_IO05 0x400120b9 /* DOUT2 */
MX6ULL_PAD_SNVS_TAMPER1__GPIO5_IO01 0x400120b9 /* DOUT3 */
MX6ULL_PAD_SNVS_TAMPER4__GPIO5_IO04 0x400120b9 /* DOUT4 */
>;
};
};
};
&iomuxc {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_gpios>;
imx6ul-evk {
pinctrl_gpios: gpiosgrp {
fsl,pins = <
MX6UL_PAD_NAND_WP_B__GPIO4_IO11 0x400120b9 /* DOUT1 */
...
}
As you can see, SION bit is set for all of the pins. The outputs are working correctly, meaning I can set them high/low. But when I try to read the actual value via sysfs, it is always a "1".
We use another output from a different pad (NAND_WP_B, as can be seen above) and there is no problem with that. This problem seems only related to SNVS_TAMPER pads in ULL processor.
Kernel version: 4.1.38-rt45-fslc+gee67fc7
Processor part: MCIMX6Y2CVM08AB
What am I missing here? How can I read back values on SNVS_TAMPER output pins?
