GPIO driver implementation does not use conform to BCM2711 (RPi4) about rust-raspberrypi-os-tutorials HOT 4 CLOSED

OMG, a brand new and shiny BCM2711 ARM Peripherals 🤩

I wasn't aware this was released recently. Nor was I aware that there are significant differences between the Pi3/Pi4 GPIO to be honest, because on my Pi4 it just worked out-of-the box, so I never questioned this.

While I cannot dive deep into your findings right now, all of this sounds plausible. I guess it makes sense split bcm2xxx_gpio.rs into Pi3 and Pi4 versions!

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I'll test it on my side and then add it to the tutorials asap!

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@abdes

I am not sure though if I should enable pup/pdn for the TX or RX when using a serial to USB cable. Maybe you could enlighten me there.

I would argue that since the USB-serial is already connected when the Pi executes the GPIO init code, NoResistor should be okay, since both the TX and RX pins are actively driven already in both directions (by the Pi and the USB serial).

It might still make sense to configure pull-up resistors for the pins. They would ensure the pin always falls back to the default value 1/high_level of the UART protocol.
I am considering introducing that change. If you want, you can test on your side if it works when you configure pull-up for both.

Best,
Andre

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Thank you

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