spi: rspi: Fix loopback mode for Dual/Quad SPI Transfers

While normal Dual and Quad SPI Transfers are unidirectional, we must do
a bidirectional transfer if loopback mode is enabled, else rx_buf is not
filled.

With spidev it seemed to work, as spidev uses the same buffer for
tranmission and reception.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index 4a1f978c3381..92bec7e91046 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -859,7 +859,9 @@ static int qspi_transfer_one(struct spi_master *master, struct spi_device *spi,
 {
         struct rspi_data *rspi = spi_master_get_devdata(master);
 
-        if (xfer->tx_buf && xfer->tx_nbits > SPI_NBITS_SINGLE) {
+        if (spi->mode & SPI_LOOP) {
+                return qspi_transfer_out_in(rspi, xfer);
+        } else if (xfer->tx_buf && xfer->tx_nbits > SPI_NBITS_SINGLE) {
                 /* Quad or Dual SPI Write */
                 return qspi_transfer_out(rspi, xfer);
         } else if (xfer->rx_buf && xfer->rx_nbits > SPI_NBITS_SINGLE) {