From f5da0820c59da3e5895735e2a4a39ff7d4c1308f Mon Sep 17 00:00:00 2001 From: Andy Shevchenko Date: Tue, 11 May 2021 17:09:12 +0300 Subject: [PATCH] spi: Assume GPIO CS active high in ACPI case [ Upstream commit 6b69546912a57ff8c31061f98e56383cc0beffd3 ] Currently GPIO CS handling, when descriptors are in use, doesn't take into consideration that in ACPI case the default polarity is Active High and can't be altered. Instead we have to use the per-chip definition provided by SPISerialBus() resource. Fixes: 766c6b63aa04 ("spi: fix client driver breakages when using GPIO descriptors") Cc: Liguang Zhang Cc: Jay Fang Cc: Sven Van Asbroeck Signed-off-by: Andy Shevchenko Tested-by: Xin Hao Link: https://lore.kernel.org/r/20210511140912.30757-1-andriy.shevchenko@linux.intel.com Signed-off-by: Mark Brown Signed-off-by: Sasha Levin --- drivers/spi/spi.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 419de3d404814..a6f1e94af13c5 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -814,16 +814,29 @@ static void spi_set_cs(struct spi_device *spi, bool enable, bool force) if (spi->cs_gpiod || gpio_is_valid(spi->cs_gpio)) { if (!(spi->mode & SPI_NO_CS)) { - if (spi->cs_gpiod) - /* polarity handled by gpiolib */ - gpiod_set_value_cansleep(spi->cs_gpiod, - enable1); - else + if (spi->cs_gpiod) { + /* + * Historically ACPI has no means of the GPIO polarity and + * thus the SPISerialBus() resource defines it on the per-chip + * basis. In order to avoid a chain of negations, the GPIO + * polarity is considered being Active High. Even for the cases + * when _DSD() is involved (in the updated versions of ACPI) + * the GPIO CS polarity must be defined Active High to avoid + * ambiguity. That's why we use enable, that takes SPI_CS_HIGH + * into account. + */ + if (has_acpi_companion(&spi->dev)) + gpiod_set_value_cansleep(spi->cs_gpiod, !enable); + else + /* Polarity handled by GPIO library */ + gpiod_set_value_cansleep(spi->cs_gpiod, enable1); + } else { /* * invert the enable line, as active low is * default for SPI. */ gpio_set_value_cansleep(spi->cs_gpio, !enable); + } } /* Some SPI masters need both GPIO CS & slave_select */ if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&