Linux/AM3352: What happens to the GPIO peripherals at the end of the shutdown sequence ?

Moses Christopher Bollavarapu

Part Number: AM3352

Tool/software: Linux

Hi,

I would like to know, what happens during the shut down sequence with respect to the peripherals like GPIO.

Consider some GPIOs are initialized to some values maybe HIGH or LOW, and then trigger shutdown. Now the GPIOs would be reset to their Reset states before the end of the shutdown sequence ?

Example:

gpio0_21 is made HIGH in Linux and then issue poweroff command, before the end of the shutdown sequence the gpio0_21 is set back to the Reset State LOW ?

over 6 years ago

0 Pavel Botev over 6 years ago

TI__Guru**** 170625 points

Moses,

I do not think GPIO peripheral is reset during shut down sequence (poweroff command). GPIO peripheral is reset only on power up sequence.

Regards,
Pavel

0 Moses Christopher Bollavarapu over 6 years ago in reply to Pavel Botev

Intellectual 980 points

Hi Pavel,

Thanks for the prompt reply.

Could you kindly let me know, if poweroff command or reboot command can control a certain GPIO ?

For Example,

Can we assign a gpio to go LOW or HIGH at the end of the poweroff sequence ?

Because, I believe that there's something that's making a gpio go low at the end of the poweroff sequence.

Also, could you kindly provide me some reference material to understand about the poweroff seqence in linux w.r.to am335x ?

0 Pavel Botev over 6 years ago in reply to Moses Christopher Bollavarapu

TI__Guru**** 170625 points

Moses,

Check if "gpio-poweroff" feature will be in help:

linux-kernel/Documentation/devicetree/bindings/power/reset/gpio-poweroff.txt
linux-kernel/Documentation/gpio/drivers-on-gpio.txt

linux-kernel/arch/arm/boot/dts/dra71-evm.dts
linux-kernel/arch/arm/boot/dts/omap3-ha-common.dtsi
linux-kernel/arch/arm/boot/dts/omap4-droid4-xt894.dts

Regards,
Pavel

0 Moses Christopher Bollavarapu over 6 years ago in reply to Pavel Botev

Intellectual 980 points

Pavel,

Thanks for the information. :-)

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Linux/AM3352: What happens to the GPIO peripherals at the end of the shutdown sequence ?