[PATCH 2/4] spi: sh-msiof: Fix handling of write value for SISTR register

[Geert Uytterhoeven <geert+renesas@xxxxxxxxx>]

From: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@xxxxxxxxxxx>

This patch changes writing to the SISTR register according to the H/W
user's manual.

The TDREQ bit and RDREQ bits of SISTR are read-only, and must be written
their initial values of zero.

Signed-off-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@xxxxxxxxxxx>
[geert: reword]
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
---
 drivers/spi/spi-sh-msiof.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index bfe4e6d4f7bff66c..101cd6aae2ea520a 100644
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -397,7 +397,8 @@ static void sh_msiof_spi_set_mode_regs(struct sh_msiof_spi_priv *p,
 
 static void sh_msiof_reset_str(struct sh_msiof_spi_priv *p)
 {
-	sh_msiof_write(p, STR, sh_msiof_read(p, STR));
+	sh_msiof_write(p, STR,
+		       sh_msiof_read(p, STR) & ~(STR_TDREQ | STR_RDREQ));
 }
 
 static void sh_msiof_spi_write_fifo_8(struct sh_msiof_spi_priv *p,
-- 
2.17.1