mmc_spi: put signals to low power off fix

The original intention was to write a zero byte to mmc to force spi
signals to low when doing power off. Somehow the spi_w8r8 call got there
so a read followed the write of single zero byte. This patch changes
that to simple write of zero byte without the following read.
This way the power off is more reliable and completely sufficient.

Signed-off-by: Jan Nikitenko <jan.nikitenko@gmail.com>
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

diff --git a/drivers/mmc/host/mmc_spi.c b/drivers/mmc/host/mmc_spi.c
index 41cc63360e43d357db2d5d42a06cf55b0abd47b3..7503b81374e0783690df20afbc88da0b02a75e85 100644 (file)
--- a/drivers/mmc/host/mmc_spi.c
+++ b/drivers/mmc/host/mmc_spi.c
@@ -1076,6 +1076,7 @@ static void mmc_spi_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                 */
                if (canpower && ios->power_mode == MMC_POWER_OFF) {
                        int mres;
+                       u8 nullbyte = 0;
 
                        host->spi->mode &= ~(SPI_CPOL|SPI_CPHA);
                        mres = spi_setup(host->spi);
@@ -1083,7 +1084,7 @@ static void mmc_spi_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
                                dev_dbg(&host->spi->dev,
                                        "switch to SPI mode 0 failed\n");
 
-                       if (spi_w8r8(host->spi, 0x00) < 0)
+                       if (spi_write(host->spi, &nullbyte, 1) < 0)
                                dev_dbg(&host->spi->dev,
                                        "put spi signals to low failed\n");