[PATCH 4/6] [Blackfin] SPI driver: fix bug - SPI duplex operation can read a dummy byte at the first transfer

[Bryan Wu]

Bug reported by Jean-Christian de Rivaz <jc@xxxxxxxx> and he also gave a patch.
http://blackfin.uclinux.org/gf/project/uclinux-dist/tracker/?action=TrackerItemEdit&tracker_item_id=3678

So revert spi_bfin5xx.c duplex operation.

Signed-off-by: Jean-Christian de Rivaz <jc@xxxxxxxx>
Signed-off-by: Bryan Wu <bryan.wu@xxxxxxxxxx>
---
 drivers/spi/spi_bfin5xx.c |   18 +++---------------
 1 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index ceb5b53..c5d4d77 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -358,14 +358,10 @@ static void u8_cs_chg_reader(struct driver_data *drv_data)
 
 static void u8_duplex(struct driver_data *drv_data)
 {
-	/* poll for SPI completion before start */
-	while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
-		cpu_relax();
-
 	/* in duplex mode, clk is triggered by writing of TDBR */
 	while (drv_data->rx < drv_data->rx_end) {
 		write_TDBR(drv_data, (*(u8 *) (drv_data->tx)));
-		while (read_STAT(drv_data) & BIT_STAT_TXS)
+		while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
 			cpu_relax();
 		while (!(read_STAT(drv_data) & BIT_STAT_RXS))
 			cpu_relax();
@@ -495,14 +491,10 @@ static void u16_cs_chg_reader(struct driver_data *drv_data)
 
 static void u16_duplex(struct driver_data *drv_data)
 {
-	/* poll for SPI completion before start */
-	while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
-		cpu_relax();
-
 	/* in duplex mode, clk is triggered by writing of TDBR */
 	while (drv_data->tx < drv_data->tx_end) {
 		write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
-		while (read_STAT(drv_data) & BIT_STAT_TXS)
+		while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
 			cpu_relax();
 		while (!(read_STAT(drv_data) & BIT_STAT_RXS))
 			cpu_relax();
@@ -516,15 +508,11 @@ static void u16_cs_chg_duplex(struct driver_data *drv_data)
 {
 	struct chip_data *chip = drv_data->cur_chip;
 
-	/* poll for SPI completion before start */
-	while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
-		cpu_relax();
-
 	while (drv_data->tx < drv_data->tx_end) {
 		cs_active(drv_data, chip);
 
 		write_TDBR(drv_data, (*(u16 *) (drv_data->tx)));
-		while (read_STAT(drv_data) & BIT_STAT_TXS)
+		while (!(read_STAT(drv_data) & BIT_STAT_SPIF))
 			cpu_relax();
 		while (!(read_STAT(drv_data) & BIT_STAT_RXS))
 			cpu_relax();
-- 
1.5.3.4
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/