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SubjectRe: [PATCH v4 3/8] spi: stm32: Add 'SPI_SIMPLEX_RX', 'SPI_3WIRE_RX' support for stm32f4
On Sat, May 23, 2020 at 12:29 AM Mark Brown <broonie@kernel.org> wrote:
>
> 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.

How about add below changes to spi-core

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 8994545..bfd465c 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -1022,7 +1022,8 @@ static int spi_map_msg(struct spi_controller
*ctlr, struct spi_message *msg)
void *tmp;
unsigned int max_tx, max_rx;

- if (ctlr->flags & (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX)) {
+ if ((ctlr->flags & (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX)) &&
+ !(msg->spi->mode & SPI_3WIRE)) {
max_tx = 0;
max_rx = 0;

for my board, lcd panel ilitek ill9341 use 3wire mode, gyro l3gd20 use
simplex rx mode.
it's has benefits to l3gd20, no impact to ili9341.
if it's fine to spi-core, i will include it to my next submits.

thanks

best regards.

Dillon

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