AM623: ‌ AM62x GPIO output control pins cannot be configured as input via direction setting.

Miao huanhuan

Part Number: AM623

Tool/software:

Hi
When we configure GPIO as output in the device tree during system startup (verified via source code/register inspection that RXACTIVE is disabled), then later attempt to switch some pins to input mode during runtime using the direction attribute, the RXACTIVE bit fails to be automatically set. Consequently, reading the GPIO pin's value returns invalid data until we manually configure the register. This behavior differs from other platforms we've used.

5 months ago

0 Anshu Madwesh 5 months ago

TI__Mastermind 18460 points

Hello,

Which Linux SDK version are you using?

Thanks,

Anshu

0 Miao huanhuan 5 months ago in reply to Anshu Madwesh

Prodigy 100 points

Hi Anshu,

Both SDK versions 08_06_00_42 and 10_01_10_04 exhibit the following problem:
When a GPIO is initially configured as output in the device tree and later switched to input mode via the direction attribute, the ‌RXACTIVE bit fails to be set automatically‌.

Regards

Miaohuanhuan

0 Anshu Madwesh 5 months ago in reply to Miao huanhuan

TI__Mastermind 18460 points

Hi Miaohuanhuan,

Just to be clear, the PIN_INPUT/OUTPUT is only related to the PADCONFIG register which will only tell the pad if its able to receive or transmit information. Hence, this won't have impact on the GPIO direction at all. The SYSFS GPIO interface is reading/writing to the GPIO registers. These two mechanisms work independently of each other.

For more information, its covered in this FAQ: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1494485/faq-processor-sdk-getting-started-with-gpios-in-linux-using-the-am62-and-am64-family-processors

From the device tree snippit you shared, its unclear what GPIOs you are using? It doesn't match the devmem output you shared as well.

Thanks,

Anshu

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AM623: ‌ AM62x GPIO output control pins cannot be configured as input via direction setting.