Uboot environment variable

Autonomous Machines Jetson & Embedded Systems Jetson TX2
1

Hello,

I have a need to toggle a GPIO pin to enable a PCIe device and then scan the bus for the device.

Once option is to toggle a uboot environment variable and reboot with a uboot function to check the variable and toggle the pin.

The other option is to add a kernel patch for a PCIe rescan. I have seen some references and wasn’t sure of the latest state.

Thanks,
John

3

Hi,

Is there a need to do this work in uboot? I think adding a patch in kernel would be more effective.

4

That would be great if it can happen before PCIe enumeration. Can I create a kernel module that would check a file and toggle the GPIO before PCIe enueration? Do you have any references to kernel modules toggling GPIO?

Thanks,
John

5

Maybe you could try some gpio API in your PCIe device driver.

For example, check devm_gpiod_get API

7

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