spi: fsl-espi: don't write ESPI_SPMODE register if the mode doesn't change

There's no need to bother the chip if the mode doesn't change.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c
index 1029bd2ff5f104337198b22e895ac38454c2e119..edb524f831a325eafcad7712c3c2bb9bd6b296e9 100644 (file)
--- a/drivers/spi/spi-fsl-espi.c
+++ b/drivers/spi/spi-fsl-espi.c
@@ -249,6 +249,7 @@ static void fsl_espi_setup_transfer(struct spi_device *spi,
        int bits_per_word = t ? t->bits_per_word : spi->bits_per_word;
        u32 pm, hz = t ? t->speed_hz : spi->max_speed_hz;
        struct spi_mpc8xxx_cs *cs = spi->controller_state;
+       u32 hw_mode_old = cs->hw_mode;
 
        /* mask out bits we are going to set */
        cs->hw_mode &= ~(CSMODE_LEN(0xF) | CSMODE_DIV16 | CSMODE_PM(0xF));
@@ -271,8 +272,10 @@ static void fsl_espi_setup_transfer(struct spi_device *spi,
 
        cs->hw_mode |= CSMODE_PM(pm);
 
-       fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPMODEx(spi->chip_select),
-                          cs->hw_mode);
+       /* don't write the mode register if the mode doesn't change */
+       if (cs->hw_mode != hw_mode_old)
+               fsl_espi_write_reg(mpc8xxx_spi, ESPI_SPMODEx(spi->chip_select),
+                                  cs->hw_mode);
 }
 
 static int fsl_espi_bufs(struct spi_device *spi, struct spi_transfer *t)