spi: bcm63xx-hsspi: Fix multi-bit mode setting

Currently the driver always sets the controller to dual data bit mode
for both tx and rx data in the profile mode control register even for
single data bit transfer. Luckily the opcode is set correctly according
to SPI transfer data bit width so it does not actually cause issues.

This change fixes the problem by setting tx and rx data bit mode field
correctly according to the actual SPI transfer tx and rx data bit width.

Fixes: 142168e ("spi: bcm63xx-hsspi: add bcm63xx HSSPI driver")
Signed-off-by: William Zhang <william.zhang@broadcom.com>
Link: https://lore.kernel.org/r/20230209200246.141520-11-william.zhang@broadcom.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-bcm63xx-hsspi.c

@@ -215,7 +215,7 @@ static int bcm63xx_hsspi_do_txrx(struct spi_device *spi, struct spi_transfer *t)
 	int step_size = HSSPI_BUFFER_LEN;
 	const u8 *tx = t->tx_buf;
 	u8 *rx = t->rx_buf;
-	u32 val;
+	u32 val = 0;
 	unsigned long limit;
 
 	bcm63xx_hsspi_set_clk(bs, spi, t->speed_hz);
@@ -233,11 +233,16 @@ static int bcm63xx_hsspi_do_txrx(struct spi_device *spi, struct spi_transfer *t)
 		step_size -= HSSPI_OPCODE_LEN;
 
 	if ((opcode == HSSPI_OP_READ && t->rx_nbits == SPI_NBITS_DUAL) ||
-	    (opcode == HSSPI_OP_WRITE && t->tx_nbits == SPI_NBITS_DUAL))
+	    (opcode == HSSPI_OP_WRITE && t->tx_nbits == SPI_NBITS_DUAL)) {
 		opcode |= HSSPI_OP_MULTIBIT;
 
-	__raw_writel(1 << MODE_CTRL_MULTIDATA_WR_SIZE_SHIFT |
-		     1 << MODE_CTRL_MULTIDATA_RD_SIZE_SHIFT | 0xff,
+		if (t->rx_nbits == SPI_NBITS_DUAL)
+			val |= 1 << MODE_CTRL_MULTIDATA_RD_SIZE_SHIFT;
+		if (t->tx_nbits == SPI_NBITS_DUAL)
+			val |= 1 << MODE_CTRL_MULTIDATA_WR_SIZE_SHIFT;
+	}
+
+	__raw_writel(val | 0xff,
 		     bs->regs + HSSPI_PROFILE_MODE_CTRL_REG(chip_select));
 
 	while (pending > 0) {