spi:improve spi read of full duplex

1.write 0 to spi send bufer only once, or spi may receive unexpect data

diff --git a/drivers/spi/rk2818_spim.c b/drivers/spi/rk2818_spim.c
index d5f408efa714d868708cbe6d5d1c1621e2f05569..2136feca7994140e5272537b713aa3ed6b030999 100755 (executable)
--- a/drivers/spi/rk2818_spim.c
+++ b/drivers/spi/rk2818_spim.c
@@ -744,8 +744,8 @@ static void do_read(struct rk2818_spi *dws)
        spi_enable_chip(dws, 0);
        rk2818_writew(dws, SPIM_CTRLR1, dws->rx_end-dws->rx-1);
        spi_enable_chip(dws, 1);                
+       rk2818_writew(dws, SPIM_DR0, 0);
        while (1) {
-               rk2818_writew(dws, SPIM_DR0, 0);
                if (dws->read(dws))
                        break;
                if (count ++ == 0x20) {