From: lyx <lyx@rock-chips.com>
Date: Sat, 25 Sep 2010 06:42:20 +0000 (-0700)
Subject: spi:improve spi read of full duplex
X-Git-Tag: firefly_0821_release~11108^2~3
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=5e36b6c6f1bfe41e49bb4d01318aa5324a5df487;p=firefly-linux-kernel-4.4.55.git

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 d5f408efa714..2136feca7994 100755
--- 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) {