spi: amd: Don't wait for a write-only transfer to finish

Return from a write-only transfer without waiting for
it to finish
But wait before a new transfer as the previous may
still happening and also wait before reading the data
from the FIFO

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Reviewed-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20210910111529.12539-4-tanureal@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-amd.c

@@ -115,11 +115,18 @@ static int amd_spi_busy_wait(struct amd_spi *amd_spi)
 	return 0;
 }
 
-static void amd_spi_execute_opcode(struct amd_spi *amd_spi)
+static int amd_spi_execute_opcode(struct amd_spi *amd_spi)
 {
+	int ret;
+
+	ret = amd_spi_busy_wait(amd_spi);
+	if (ret)
+		return ret;
+
 	/* Set ExecuteOpCode bit in the CTRL0 register */
 	amd_spi_setclear_reg32(amd_spi, AMD_SPI_CTRL0_REG, AMD_SPI_EXEC_CMD, AMD_SPI_EXEC_CMD);
-	amd_spi_busy_wait(amd_spi);
+
+	return 0;
 }
 
 static int amd_spi_master_setup(struct spi_device *spi)
@@ -178,6 +185,7 @@ static inline int amd_spi_fifo_xfer(struct amd_spi *amd_spi,
 			amd_spi_clear_fifo_ptr(amd_spi);
 			/* Execute command */
 			amd_spi_execute_opcode(amd_spi);
+			amd_spi_busy_wait(amd_spi);
 			/* Read data from FIFO to receive buffer  */
 			for (i = 0; i < rx_len; i++)
 				buf[i] = amd_spi_readreg8(amd_spi, AMD_SPI_FIFO_BASE + tx_len + i);