hi Mark, Thanks for reviewing.
On Fri, May 22, 2020 at 7:36 PM Mark Brown <broo...@kernel.org> wrote: > > On Mon, May 18, 2020 at 07:09:20PM +0800, dillon.min...@gmail.com wrote: > > > 2, use stm32 spi's "In full-duplex (BIDIMODE=0 and RXONLY=0)", as tx_buf is > > null, we must add dummy data sent out before read data. > > so, add stm32f4_spi_tx_dummy() to handle this situation. > > There are flags SPI_CONTROLLER_MUST_TX and SPI_CONTROLLER_MUST_RX flags > that the driver can set if it needs to, no need to open code this in the > driver. Yes, after check SPI_CONTROLLER_MUST_TX in drivers/spi/spi.c , it's indeed to meet this situation, i will try it and sumbmit a new patch. thanks. best regards Dillon