On Fri, May 22, 2020 at 11:59:25PM +0800, dillon min wrote:

> but, after spi-core create a dummy tx_buf or rx_buf, then i can't get
> the correct spi_3wire direction.
> actually, this dummy tx_buf is useless for SPI_3WIRE. it's has meaning
> for SPI_SIMPLE_RX mode,
> simulate SPI_FULL_DUMPLEX

Oh, that's annoying.  I think the fix here is in the core, it should
ignore MUST_TX and MUST_RX in 3WIRE mode since they clearly make no
sense there.