spi: Fix regression in spi-bitbang-txrx.h

This patch fixes a regression introduced by commit 232a5adc5199 ("spi:
bitbang: only toggle bitchanges"). The attempt to optimize writes of
consecutive bit patterns broke most of the combinations of word size
and SPI modes due to selecting the wrong bit as the MSB value.

Fixes: 232a5adc5199 (spi: bitbang: only toggle bitchanges)
Signed-off-by: Lars Persson <larper@axis.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org

diff --git a/drivers/spi/spi-bitbang-txrx.h b/drivers/spi/spi-bitbang-txrx.h
index 06b34e5bcfa37eaf9eba3e9ff8d1d017454dc81d..47bb9b898dfdc6ab18ae5fd10349f23882200e4f 100644 (file)
--- a/drivers/spi/spi-bitbang-txrx.h
+++ b/drivers/spi/spi-bitbang-txrx.h
@@ -49,7 +49,7 @@ bitbang_txrx_be_cpha0(struct spi_device *spi,
 {
        /* if (cpol == 0) this is SPI_MODE_0; else this is SPI_MODE_2 */
 
-       bool oldbit = !(word & 1);
+       u32 oldbit = (!(word & (1<<(bits-1)))) << 31;
        /* clock starts at inactive polarity */
        for (word <<= (32 - bits); likely(bits); bits--) {
 
@@ -81,7 +81,7 @@ bitbang_txrx_be_cpha1(struct spi_device *spi,
 {
        /* if (cpol == 0) this is SPI_MODE_1; else this is SPI_MODE_3 */
 
-       bool oldbit = !(word & (1 << 31));
+       u32 oldbit = (!(word & (1<<(bits-1)))) << 31;
        /* clock starts at inactive polarity */
        for (word <<= (32 - bits); likely(bits); bits--) {