UART without pullup - machine.mem32 access

[helgerustad]

Hello.
I am using the UART on the ESP32 with MicroPython. The pull-up on the RXD pin seems to be automatically enabled but causes trouble since my external driver is weak. I cannot find a way to disable the pull-up.

I investigate whether it is possible to use ESP32 registers directly. But this is also problematic.
When I read machine.mem32[0x3ff49028] I expect to see in the result whether pull-up/pull-down is enabled for GPIO_26, but this register always reads the same whether the pull-up of pull-down is enabled with the micropython PIN driver.

Does anyone know what is wrong here?
Regards Helge