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

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Commit f3186dd876 ("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: f3186dd876 ("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+
This commit is contained in:
Lukas Wunner 2020-02-18 13:08:00 +01:00 committed by Mark Brown
parent 136b5cd2e2
commit 138c9c32f0
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 5 additions and 0 deletions
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5
drivers/spi/spidev.c
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@ -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);