[PATCH 4/4] spi: synquacer: simplify tx completion checking

[Masahisa Kojima]

There is a TX-FIFO and Shift Register empty(TFES) status
bit in spi controller. This commit checks the TFES bit
to wait the TX transfer completes.

Signed-off-by: Masahisa Kojima <masahisa.kojima at linaro.org>
Signed-off-by: Satoru Okamoto <okamoto.satoru at socionext.com>
---
 drivers/spi/spi-synquacer.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/spi/spi-synquacer.c b/drivers/spi/spi-synquacer.c
index 5e1b3aedc7..0cae3dfc77 100644
--- a/drivers/spi/spi-synquacer.c
+++ b/drivers/spi/spi-synquacer.c
@@ -45,6 +45,7 @@
 #define RXF		0x20
 #define RXE		0x24
 #define RXC		0x28
+#define TFES		1
 #define TFLETE		4
 #define TSSRS		6
 #define RFMTE		5
@@ -345,13 +346,10 @@ static int synquacer_spi_xfer(struct udevice *dev, unsigned int bitlen,
 		if (priv->tx_words) {
 			write_fifo(priv);
 		} else {
-			u32 len;
-
-			do { /* wait for shifter to empty out */
+			/* wait for shifter to empty out */
+			while (!(readl(priv->base + TXF) & BIT(TFES)))
 				cpu_relax();
-				len = readl(priv->base + DMSTATUS);
-				len = (len >> TX_DATA_SHIFT) & TX_DATA_MASK;
-			} while (tx_buf && len);
+
 			busy &= ~BIT(TXBIT);
 		}
 	}
-- 
2.17.1