[PATCH 5.10 20/30] Revert "spi: mediatek: fix fifo rx mode"

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

From: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

This reverts commit 2435dcfd16ac482803c6ecf2ba0d2a0553214d54 which is
commit 3a70dd2d050331ee4cf5ad9d5c0a32d83ead9a43 upstream.

It has been found to have problems.

Reported-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Cc: Peter Hess <peter.hess@xxxxxxxxxx>
Cc: Frank Wunderlich <frank-w@xxxxxxxxxxxxxxx>
Cc: Mark Brown <broonie@xxxxxxxxxx>
Cc: Sasha Levin <sashal@xxxxxxxxxx>
Link: https://lore.kernel.org/r/efee3a58-a4d2-af22-0931-e81b877ab539@xxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/spi/spi-mt65xx.c |   16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

--- a/drivers/spi/spi-mt65xx.c
+++ b/drivers/spi/spi-mt65xx.c
@@ -434,23 +434,13 @@ static int mtk_spi_fifo_transfer(struct
 	mtk_spi_setup_packet(master);
 
 	cnt = xfer->len / 4;
-	if (xfer->tx_buf)
-		iowrite32_rep(mdata->base + SPI_TX_DATA_REG, xfer->tx_buf, cnt);
-
-	if (xfer->rx_buf)
-		ioread32_rep(mdata->base + SPI_RX_DATA_REG, xfer->rx_buf, cnt);
+	iowrite32_rep(mdata->base + SPI_TX_DATA_REG, xfer->tx_buf, cnt);
 
 	remainder = xfer->len % 4;
 	if (remainder > 0) {
 		reg_val = 0;
-		if (xfer->tx_buf) {
-			memcpy(&reg_val, xfer->tx_buf + (cnt * 4), remainder);
-			writel(reg_val, mdata->base + SPI_TX_DATA_REG);
-		}
-		if (xfer->rx_buf) {
-			reg_val = readl(mdata->base + SPI_RX_DATA_REG);
-			memcpy(xfer->rx_buf + (cnt * 4), &reg_val, remainder);
-		}
+		memcpy(&reg_val, xfer->tx_buf + (cnt * 4), remainder);
+		writel(reg_val, mdata->base + SPI_TX_DATA_REG);
 	}
 
 	mtk_spi_enable_transfer(master);