I2C with DMA fails

[eliclement]

I am using the pyb.I2C legacy because there is a DMA option but the DMA is not working and causing a hang when using dma=True on a pyb.I2C instance on a STM32H7.

from pyb import I2C
i2c=I2C(3, I2C.MASTER, baudrate=100_000, dma=True)

It all fails when using I2C.mem_read, I2C.mem_write, I2C.recv and I2C.recv.

FYI: When setting dma=False in the init, the transfers work.

Ideas?