Unverified Commit 138c9c32 authored Feb 18, 2020 by Lukas Wunner Committed by Mark Brown Feb 21, 2020

spi: spidev: Fix CS polarity if GPIO descriptors are used



Commit f3186dd8 ("spi: Optionally use GPIO descriptors for CS GPIOs")
amended of_spi_parse_dt() to always set SPI_CS_HIGH for SPI slaves whose
Chip Select is defined by a "cs-gpios" devicetree property.

This change broke userspace applications which issue an SPI_IOC_WR_MODE
ioctl() to an spidev:  Chip Select polarity will be incorrect unless the
application is changed to set SPI_CS_HIGH.  And once changed, it will be
incompatible with kernels not containing the commit.

Fix by setting SPI_CS_HIGH in spidev_ioctl() (under the same conditions
as in of_spi_parse_dt()).

Fixes: f3186dd8 ("spi: Optionally use GPIO descriptors for CS GPIOs")
Reported-by: Simon Han <z.han@kunbus.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/fca3ba7cdc930cd36854666ceac4fbcf01b89028.1582027457.git.lukas@wunner.de


Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: stable@vger.kernel.org # v5.1+

parent 136b5cd2

drivers/spi/spidev.c

+5 −0

Original line number	Diff line number	Diff line
		@@ -396,6 +396,7 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
		else
		retval = get_user(tmp, (u32 __user *)arg);
		if (retval == 0) {
		struct spi_controller *ctlr = spi->controller;
		u32 save = spi->mode;

		if (tmp & ~SPI_MODE_MASK) {
		@@ -403,6 +404,10 @@ spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
		break;
		}

		if (ctlr->use_gpio_descriptors && ctlr->cs_gpiods &&
		ctlr->cs_gpiods[spi->chip_select])
		tmp \|= SPI_CS_HIGH;

		tmp \|= spi->mode & ~SPI_MODE_MASK;
		spi->mode = (u16)tmp;
		retval = spi_setup(spi);

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