Commit 3b52093d authored Dec 04, 2019 by Linus Walleij Committed by Alexandre Belloni Dec 10, 2019

rtc: ds1343: Do not hardcode SPI mode flags



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@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20191204225731.20306-1-linus.walleij@linaro.org


Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

parent 519d6370

drivers/rtc/rtc-ds1343.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -365,9 +365,12 @@ static int ds1343_probe(struct spi_device *spi)
		priv->spi = spi;

		/* 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)

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