Hi,
I have imx8mp Verdin system and need to change SODIMM 64 functionality to GPIO:
To disable this pin:
pinctrl_flexspi0: flexspi0grp {
fsl,pins =
<MX8MP_IOMUXC_NAND_READY_B__GPIO3_IO16 0x82>; /* SODIMM 64 */
I did it directly in imx8mp-verdin.dtsi file and replaced default with disabled:
&flexspi {disabled ”;
Then I have created a new flexspi-to-gpio.dts file below and created a new group with a new function:
/dts-v1/;
#include <dt-bindings/gpio/gpio.h>
// A) Header file with pin definitions#include <imx8mp-pinfunc.h>
/ {
&iomuxc {
// Append your custom pin group to the iomuxc defaults
pinctrl-0 = <&pinctrl_output_pins>;
// Define your pin mapping group
// Added for gpio-80 (SODIMM_64)
pinctrl_output_pins: gpiosodimm64grp {
fsl,pins = <
MX8MP_IOMUXC_NAND_READY_B__GPIO3_IO16 0x184
>;
};
};
I added flexspi-to-gpio.dts to tcbuild.yaml file:
overlays:
device-trees/overlays/flexspi-to-gpio.dts
run and deployed the nee OS image but the new function is not working when tried to open it programmatically , the C++ function call below fails for this pin
line = gpiod_chip_get_line(currentGpioChip, currentGpioLine);
Hi, I’m the Toradex AI Assistant.
I might make mistakes or occasionally get you wrong. Our support team will step in if needed.
I can guide you on pin multiplexing for SODIMM 64 on the Verdin iMX8M Plus. However, to provide the most accurate instructions, could you let me know which version of Torizon OS or BSP you are running? You can find this by running tdx-info on your device.(1) (2)
That said, here’s the general approach based on the documentation:
Modifying base device tree files directly (imx8mp-verdin.dtsi) is not recommended for production. Device tree overlays are the proper method.(1) (2)
Disabling FlexSPI : Setting pinctrl-names = "disabled" doesn’t actually disable the peripheral. You need to set status = "disabled" on the &flexspi node.(3)
Overlay structure : Your overlay should disable the FlexSPI peripheral and configure the pin as GPIO.(1)
Your flexspi-to-gpio.dts overlay should look like this:
/dts-v1/;
/plugin/;
#include <dt-bindings/gpio/gpio.h>
#include "imx8mp-pinfunc.h"
/ {
compatible = "toradex,verdin-imx8mp";
};
&flexspi {
status = "disabled";
};
&iomuxc {
pinctrl_sodimm_64_gpio: sodimm64gpiogrp {
fsl,pins = <
MX8MP_IOMUXC_NAND_READY_B__GPIO3_IO16 0x184
>;
};
};
&gpio3 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sodimm_64_gpio>;
};
(1) (3)
Disable FlexSPI : The &flexspi { status = "disabled"; } section releases SODIMM 64 from FlexSPI control.(3) Pin configuration : 0x184 configures the pin with weak pull-down.(1) GPIO controller : The pin is assigned to &gpio3 since it’s GPIO3_IO16.(1) (3)
After applying the overlay, you can control the GPIO direction from Linux using tools like gpioset.(1) (3)
For more details on writing device tree overlays, see the comprehensive guide.(1)
Best regards,
Did you like my answer?
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For follow-up questions to me, please use @ToradexAI
I tried exactly AI example and still the same error.
flexspi-to-gpio.dts (440 Bytes)
Hers is what I have for the command below and I do not see any GPIO3_IO16 :
cat /sys/kernel/debug/pinctrl/pinctrl-handles
Requested pin control handlers their pinmux maps:
I can see your overlay is being applied (the sodimm64gpiogrp group appears in the pinctrl output), but there’s a critical issue: you’re assigning the pin to the wrong GPIO controller .(1) (2)
SODIMM 64 (GPIO3_IO16) belongs to GPIO controller 3 (gpio3), but your overlay assigns it to gpio1 (device 30220000.gpio). This is why you see:
device: 30220000.gpio current state: default
state: default
type: MUX_GROUP controller 30330000.pinctrl group: sodimm64gpiogrp (0) function: pinctrl (0)
type: CONFIGS_PIN controller 30330000.pinctrl pin MX8MP_IOMUXC_NAND_READY_B (72)config 00000184
The pin is configured, but it’s not accessible through the correct GPIO controller.(1) (2)
Your flexspi-to-gpio.dts should assign the pin to &gpio3, not &gpio1:
/dts-v1/;
/plugin/;
#include <dt-bindings/gpio/gpio.h>
#include "imx8mp-pinfunc.h"
/ {
compatible = "toradex,verdin-imx8mp";
};
&flexspi {
status = "disabled";
};
&iomuxc {
pinctrl_sodimm_64_gpio: sodimm64gpiogrp {
fsl,pins = <
MX8MP_IOMUXC_NAND_READY_B__GPIO3_IO16 0x184
>;
};
};
&gpio3 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sodimm_64_gpio>;
};
(1) (2)
After rebuilding and deploying the overlay:
Check the pin assignment:
cat /sys/kernel/debug/pinctrl/pinctrl-handles | grep -A2 "30240000.gpio"
You should now see the pin assigned to GPIO controller 3 (30240000.gpio).(1)
Access the GPIO:
GPIO3_IO16 corresponds to gpiochip2, line 16 in Linux
Use: gpioset gpiochip2 16=1 to set it high(1)
In your C++ code:
// Open GPIO chip 2 (gpio3)
currentGpioChip = gpiod_chip_open_by_name("gpiochip2");
currentGpioLine = 16;
line = gpiod_chip_get_line(currentGpioChip, currentGpioLine);
The key fix is changing &gpio1 to &gpio3 in your overlay.(1) (2)
Best regards,
Did you like my answer?
If I answered your question, please tick the “Solution” checkbox .
For follow-up questions to me, please use @ToradexAI
I did use initially gpio3 not &gpio1
The command below shows nothing.
cat /sys/kernel/debug/pinctrl/pinctrl-handles | grep -A2 “30240000.gpio”
PS. Can anyone jump in and take a look ?
What do you mean “initially”?
&gpio3 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_sodimm_64_gpio>;
status = "okay";
};
You should see SODIMM 64 as line offset 16 on the GPIO3 controller.tcb ?
which BSP you are using as base
Guessing, this is the answer
Software summary
------------------------------------------------------------
Bootloader: U-Boot
Kernel version: 6.6.23-7.0.0-devel-g5545cedda0e3 #1-Torizon SMP PREEMPT Wed Aug 28 13:26:04 UTC 2024
Kernel command line: root=LABEL=otaroot rootfstype=ext4 quiet logo.nologo vt.global_cursor_default=0 plymouth.ignore-serial-consoles splash fbcon=map:3 ostree=/ostree/boot.1/torizon/3eaf173f53ce793f5a773022c96c609e266ebb8c63ece19e4e3289fd53797690/0 clk-imx8mp.mcore_booted=1
Distro name: NAME="Torizon OS with PREEMPT_RT"
Distro version: VERSION_ID=7.0.0-devel-202409-build.1
Hostname: verdin-imx8mp-08745920
------------------------------------------------------------
Hardware info
------------------------------------------------------------
HW model: Toradex Verdin iMX8M Plus on Dahlia Board
Toradex version: 0063 V1.1B
Serial number: 08745920
Processor arch: aarch64
I used gpio3 and never assigned to gpio1.
What I realized is that to open the line with C++ function gpiod_chip_get_line() I have to pass not GPIO number 80 from the line below:
gpiochip2: GPIOs 64-95, parent: platform/30220000.gpio, 30220000.gpio:
...
gpio-80 (SODIMM_64 )
...
Instead, I think I have to pass an offset that is 16 (GPIO3_IO16 3 - group, 16 - offset)
Is it correct ?
Thank you
Yes, that is correct.
This output:
gpiochip2: GPIOs 64-95, parent: platform/30220000.gpio
...
gpio-80 (SODIMM_64)
uses the old global GPIO numbering :
global GPIO number = chip base + line offset
= 64 + 16
= 80
But gpiod_chip_get_line() expects the line offset within the selected GPIO chip , not the global GPIO number. GPIO character-device lines are identified by offsets from 0 to number_of_lines - 1.
alex.tx:
mber_of_lin
Hi,
I can open the pin successfully and when set it to high or low state , the command below shows correct value:
cat /sys/kernel/debug/gpio
When it has a HIGH state:
gpiochip0: GPIOs 0-31, parent: platform/30200000.gpio, 30200000.gpio:gpio-16 ( |WhiteKingLinux ) out hi
On LOW state:
gpiochip0: GPIOs 0-31, parent: platform/30200000.gpio, 30200000.gpio:
gpio-8 (SODIMM_218 |WhiteKingLinux ) in logpio-16 ( |WhiteKingLinux ) out lo
But when we measure the real voltage on pin X19 - 11 - it is always 0 volts:
Can it be related that the command cat /sys/kernel/debug/gpio does not show SODIMM # for gpio-16 ? See above output HIGH LOW
Also Is the new pin value 0x184 is correct in the added Device Tree?
&iomuxc {0x184
;
Yes, the 0x184 is a correct value for GPIO pinmuxing.
Please try to use gpioset gpiochip2 16=1 and gpioset gpiochip2 16=0 commands and check votage level at sodimm 64
That worked.
PS.A little confusing that it is located in gpiochip0 but I have to still select chip 2 when set high/low.
Thanks again
