From mboxrd@z Thu Jan 1 00:00:00 1970 From: Heiner Kallweit Subject: [PATCH 2/2] spi: fsl-espi: don't write ESPI_SPMODE register if the mode doesn't change Date: Fri, 4 Nov 2016 21:01:12 +0100 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: "linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" To: Mark Brown Return-path: In-Reply-To: Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: There's no need to bother the chip if the mode doesn't change. Signed-off-by: Heiner Kallweit --- drivers/spi/spi-fsl-espi.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/spi/spi-fsl-espi.c b/drivers/spi/spi-fsl-espi.c index 1029bd2..edb524f 100644 --- 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) -- 2.10.1 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html