spi: sh-msiof: Fix handling of write value for SISTR register

BugLink: https://bugs.launchpad.net/bugs/1836287
commit 31a5fae4c5a009898da6d177901d5328051641ff upstream.

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@renesas.com>
[geert: reword]
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/spi/spi-sh-msiof.c b/drivers/spi/spi-sh-msiof.c
index 26fb95dcd4441b112584e4b0f78213f7bb6fb28f..c6a39fc40cdc069a23140fd966294267c36faec1 100644 (file)
--- a/drivers/spi/spi-sh-msiof.c
+++ b/drivers/spi/spi-sh-msiof.c
@@ -384,7 +384,8 @@ 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,