In my spi protocol driver I send large buffers of data to be transferred.  I am not interested in the data received so I leave the rx_buf as NULL.    In the controller driver they have code to implement this use case: https://github.com/allwinner-zh/linux-3.4-sunxi/blob/6964d467510849e3e262518cb87bff7ef92e01f5/drivers/spi/spi-sunxi.c#L1003 However the transfer never completes and the kernel logs a time out for each transfer after 120 seconds.   I have tried modifying the driver with variou