Mity CPU Platforms » MitySOM-AM62, MitySOM-AM62A, & MitySOM-AM62P

Hi Paul,

By default, the MCU_GPIO peripheral is controlled in the linux kernel for the devkit. (see the arch/arm64/boot/dts/k3-am62x-mitysom-devkit.dts file which enables it).

I am wondering if perhaps there is a conflict between the Cortex-A53 cluster and the MCU because they are both trying to control the gpio peripheral.

For sanity, can you not load the MCU and just use the sysfs gpio (let me know if you need commands) to poke the pins in question and see if the pins toggle? I am pretty sure we test this at some point in our production cycle.

You may need to disable the mcu_gpio0 device in the device tree for the linux ARM cluster to get it to work. I think most of those go to the expansion header expect for one pin that is used for the touch / LVDS screen interface.

I think the wkup_i2c0 device should also be disabled on the linux side by default.

-Mike

Thanks Mike

I think I have set up the GPIO lines correctly. I followed the steps described in the following wiki
https://support.criticallink.com/redmine/projects/mitysom_am62x/wiki/Example_-_User_level_GPIO_Access
I came up with gpio531 and gpio532

With the MCU not being loaded I ran the following commands
echo 531 >/sys/class/gpio/export
echo 532 >/sys/class/gpio/export
echo out >/sys/class/gpio/gpio531/direction
echo out >/sys/class/gpio/gpio532/direction
echo 1 >/sys/class/gpio/gpio531/value
echo 1 >/sys/class/gpio/gpio532/value
But there was no change of state on either line

I couldn’t see anything in the dts file that suggested that GPIO0_19 or GPIO0_20 were mapped to the Arm, but there are entries under the mcu_gpio_p3_pins_default section

mcu_gpio_p3_pins_default: mcu-p3-default-pins {
pinctrl-single,pins = <
/* P3 Connector /
AM62X_MCU_IOPAD(0x0000, PIN_INPUT, 0) / (E8) MCU_SPI0_CS0 /
AM62X_MCU_IOPAD(0x0004, PIN_INPUT_PULLDOWN, 7) / (B8) MCU_SPI0_CS1.MCU_GPIO0_1 /
AM62X_MCU_IOPAD(0x0008, PIN_INPUT, 0) / (A7) MCU_SPI0_CLK /
AM62X_MCU_IOPAD(0x000c, PIN_INPUT, 0) / (D9) MCU_SPI0_D0 /
AM62X_MCU_IOPAD(0x0010, PIN_INPUT, 0) / (C9) MCU_SPI0_D1 /
AM62X_MCU_IOPAD(0x0044, PIN_INPUT, 7) / (A8) MCU_I2C0_SCL.MCU_GPIO0_17 /
AM62X_MCU_IOPAD(0x0048, PIN_INPUT, 7) / (D10) MCU_I2C0_SDA.MCU_GPIO0_18 /
AM62X_MCU_IOPAD(0x004c, PIN_INPUT, 7) / (B9) WKUP_I2C0_SCL.MCU_GPIO0_19 /
AM62X_MCU_IOPAD(0x0050, PIN_INPUT, 7) / (A9) WKUP_I2C0_SDA.MCU_GPIO0_20 */

;

};

I have highlighted GPIO0_19 and GPIO0_20 above. GPIO0_1 is also highlighted and I am able to change the state of this pin.

Paul

Hi Paul,

To confirm, you are using a standard AM62x SOM, correct (not an AM62Ax or AM62Px)?

Thanks,
Mike

Also are you testing this on our devkit or on a custom design? If a custom design, would you be willing to email it to us for review?

Hello Paul,

We have replicated this issue on our end. I am using a 62x with our latest SDK (11.01) and found that MCU_GPIO0_17 through MCU_GPIO0_20 were not changing after a gpio set. We also noticed MCU_GPIO0_0 through MCU_GPIO0_4 were changing appropriately, similar to what you reported initially.

root@mitysom-am62x:~# for i in $(seq 0 23); do echo $i; gpio MCU_GPIO0_$i set 0; done
...
root@mitysom-am62x:~# cat /sys/kernel/debug/gpio | grep MCU            
 gpio-512 (MCU_GPIO0_0         |sysfs               ) out lo 
 gpio-513 (MCU_GPIO0_1         |sysfs               ) out lo 
 gpio-514 (MCU_GPIO0_2         |sysfs               ) out lo 
 gpio-515 (MCU_GPIO0_3         |sysfs               ) out lo 
 gpio-516 (MCU_GPIO0_4         |sysfs               ) out lo 
 gpio-529 (MCU_GPIO0_17        |sysfs               ) out lo 
 gpio-530 (MCU_GPIO0_18        |sysfs               ) out lo 
 gpio-531 (MCU_GPIO0_19        |sysfs               ) out lo 
 gpio-532 (MCU_GPIO0_20        |sysfs               ) out lo 

root@mitysom-am62x:~# for i in $(seq 0 23); do echo $i; gpio MCU_GPIO0_$i set 1; done
...
root@mitysom-am62x:~# cat /sys/kernel/debug/gpio | grep MCU
 gpio-512 (MCU_GPIO0_0         |sysfs               ) out hi 
 gpio-513 (MCU_GPIO0_1         |sysfs               ) out hi 
 gpio-514 (MCU_GPIO0_2         |sysfs               ) out hi 
 gpio-515 (MCU_GPIO0_3         |sysfs               ) out hi 
 gpio-516 (MCU_GPIO0_4         |sysfs               ) out hi 
 gpio-529 (MCU_GPIO0_17        |sysfs               ) out lo 
 gpio-530 (MCU_GPIO0_18        |sysfs               ) out lo 
 gpio-531 (MCU_GPIO0_19        |sysfs               ) out lo 
 gpio-532 (MCU_GPIO0_20        |sysfs               ) out lo 

The other GPIO's are not pinmuxxed as GPIO's, so we are ignoring them as we would not expect them to change.
MCU_GPIO0_17 through MCU_GPIO0_20 are WKUP pins so this could be related to the issue in some way? We will look into this.