The current use of mode flags to us SPI_MODE_3 and SPI_CS_HIGH is fragile: it overwrites anything already assigned by the SPI core. Change it thusly: - Just |= the SPI_MODE_3 so we keep other flags - Assign ^= SPI_CS_HIGH since we might be active high already, and that is usually the case with GPIOs used for chip select, even if they are in practice active low. Add a comment clarifying why ^= SPI_CS_HIGH is the right choice here. Reported-by: Mark Brown <broonie@xxxxxxxxxx> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> --- drivers/rtc/rtc-ds1343.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/rtc/rtc-ds1343.c b/drivers/rtc/rtc-ds1343.c index fa6de31d5793..105a2fd93583 100644 --- a/drivers/rtc/rtc-ds1343.c +++ b/drivers/rtc/rtc-ds1343.c @@ -484,9 +484,12 @@ static int ds1343_probe(struct spi_device *spi) mutex_init(&priv->mutex); /* RTC DS1347 works in spi mode 3 and - * its chip select is active high + * its chip select is active high. Active high should be defined as + * "inverse polarity" as GPIO-based chip selects can be logically + * active high but inverted by the GPIO library. */ - spi->mode = SPI_MODE_3 | SPI_CS_HIGH; + spi->mode |= SPI_MODE_3; + spi->mode ^= SPI_CS_HIGH; spi->bits_per_word = 8; res = spi_setup(spi); if (res) -- 2.23.0
