bfin: discard invalid data and clear RXS in bf5xx spi driver

There may be dirty data in RDBR, so we should discard invalid data.
This operation also clears RXS bit in STAT register.

Signed-off-by: Scott Jiang <scott.jiang.linux@gmail.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>

diff --git a/drivers/spi/bfin_spi.c b/drivers/spi/bfin_spi.c
index 0fa131b21df7232d0786e2e52130bea77f0fda0f..a9a4d92c3e719b0a1f215393ac7fc22de6cae8cf 100644 (file)
--- a/drivers/spi/bfin_spi.c
+++ b/drivers/spi/bfin_spi.c
@@ -248,6 +248,8 @@ void spi_release_bus(struct spi_slave *slave)
 static int spi_pio_xfer(struct bfin_spi_slave *bss, const u8 *tx, u8 *rx,
                        uint bytes)
 {
+       /* discard invalid data and clear RXS */
+       read_SPI_RDBR(bss);
        /* todo: take advantage of hardware fifos  */
        while (bytes--) {
                u8 value = (tx ? *tx++ : CONFIG_BFIN_SPI_IDLE_VAL);