[U-Boot] [PATCH v2 2/5] DW SPI: fix transmit only mode

[Eugeniy Paltsev]

In current implementation we get -ETIMEDOUT error when we try to use
transmit only mode (SPI_TMOD_TO)
This happens because in transmit only mode input FIFO never gets any data
which breaks our logic in dw_reader(): we are waiting until RX data will be
ready in dw_reader, but this newer happens, so we return with error.

Fix that by using SPI_TMOD_TR instead of SPI_TMOD_TO which allows to use
RX FIFO.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev at synopsys.com>
---
Changes v1->v2:
 * None.

 drivers/spi/designware_spi.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
index 5e196b21c9..3296441606 100644
--- a/drivers/spi/designware_spi.c
+++ b/drivers/spi/designware_spi.c
@@ -361,7 +361,11 @@ static int dw_spi_xfer(struct udevice *dev, unsigned int bitlen,
 	else if (rx)
 		priv->tmode = SPI_TMOD_RO;
 	else
-		priv->tmode = SPI_TMOD_TO;
+		/*
+		 * In transmit only mode (SPI_TMOD_TO) input FIFO never gets
+		 * any data which breaks our logic in poll_transfer() above.
+		 */
+		priv->tmode = SPI_TMOD_TR;
 
 	cr0 &= ~SPI_TMOD_MASK;
 	cr0 |= (priv->tmode << SPI_TMOD_OFFSET);
-- 
2.14.3