TDA4VM: GPIO output value always 0

Hi,

Can you try with PIN_INPUT instead of PIN_OUTPUT.

For example we have a working GPIO mux;

        sw11_button_pins_default: sw11-button-pins-default {
                pinctrl-single,pins = <
                        J721E_WKUP_IOPAD(0xcc, PIN_INPUT, 7) /* (G28) WKUP_GPIO0_7 */
                >;
        };

Let me know if that help you. If no further questions please click on verify answer.

Best Regards,
Keerthy

Hi Veitch,

Let us take your first example GPIO0_14.

Now AG24 is the PAD that needs to be configured to GPIO mode.



Use the below command from Linux command prompt:

devmem2 0x11c038 w 0x08050007

So pin muxing is done.

Let us get to GPIO layer:

cat /sys/class/gpio/gpiochip252/label
600000.gpio

We are interested in GPIO0 which is labelled 600000.gpio

root@j7-evm:~# cat /sys/class/gpio/gpiochip252/base
252

Base is 252 in my setup so I add 14 to 252. 252 + 14 = 266.


echo 266 > /sys/class/gpio/export

echo out > /sys/class/gpio/gpio266/direction

echo 1 > /sys/class/gpio/gpio266/value

cat /sys/class/gpio/gpio266/value
1

Hope this gives you the right sequence. If no further questions please click on verify answer.

Best Regards,
Keerthy

Hi Veitch,

I Optimized the pinmux value. Basically 'devmem2 0x11c038 w 0x00040007'

Should do the trick for you.

Veitch Kyrie said:

1.Should I do this every time for each gpio manually? Could I configure the direction or value of gpio in dts? 

DTS value for 0x00040007 corresponds to PIN_INPUT | 0x7. This should have ideally helped you. It seems like
your DTS setting is getting overwritten. You can try to dump out the value of register:

devmem2 0x11c038 w

Let us check if your DTS setting to PIN_INPUT is really taking effect.

Can you let me know if that is getting over written by pin muxing of some other node.

Veitch Kyrie said:

3.How should I do if I want configure the gpio output state in kernel for the power on timing of outside peripherals devices? Is there an referrence about configuring gpio in kernel.

You can try gpio-hog in dts. That should switch the GPIO to output and also set the value to some default.

Ex: Refer gpio-hog instances in arch/arm64/boot/dts/ti/k3-j721e-common-proc-board.dts

Best Regards,
Keerthy

Hi,

You are configuring the wrong pinmux register. Check the data sheet: https://www.ti.com/lit/ds/symlink/dra829v.pdf?ts=1636071319638&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FDRA829V

Page: 137

The right address of the AH24 is 0x11c068

Could you try with that?

Veitch Kyrie said:

what should I do if I need to do some delay for the gpio output in kernel? since the device requires a power-on sequence which is control by gpio.

GPIO-HOG will happen when the parent gpio controller driver is probed. Is that good enough for you?

- Keerthy

Veitch Kyrie said:

Our platform is TDA4VM instead of DRA829, why should we use the address of dra829?

TDA4VM/DRA829/J721e all mean the same.

Veitch Kyrie said:

I want to do something like GPIO0_0(output high)--->delay(5ms)--->GPIO0_1(output high) , the point is how to do the delay in dts, can it be implemented by GPIO-HOG?

No GPIO-HOG will enable a one time setting of GPIO level.

Veitch Kyrie said:

k3-j721e-eaik.dts

This is Edge-AI-Kit. This is used for a different variant of TDA4VM board. It is called the SK board. You can focus on the k3-j721e-common-proc-board.dts.

Veitch Kyrie said:

k3-j721e-common-proc-board-infotainment.dts

This is an overlay for infotainment peripherals. This is applied on top of  k3-j721e-common-proc-board.dts. Some basics of overlays on DTS is here: https://www.kernel.org/doc/html/latest/devicetree/overlay-notes.html

If no other questions please click on verify answer.

- Keerthy