Commit 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API") not only switched to the gpiod API, but also inverted / changed the polarity of the GPIO.
According to the PCI specification, the RST# pin is an active-low signal. However, most of the device trees that have been widely used for a long time (mainly in the openWrt project) define this GPIO as active-high and the old driver code inverted the signal internally.
Apparently there are actually boards where the reset gpio must be operated inverted. For this reason, we cannot use the GPIOD_OUT_LOW/HIGH flag for initialization. Instead, we must explicitly set the gpio to value 1 in order to take into account any "GPIO_ACTIVE_LOW" flag that may have been set.
In order to remain compatible with all these existing device trees, we should therefore keep the logic as it was before the commit.
Fixes: 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API") Cc: stable@vger.kernel.org Signed-off-by: Martin Schiller ms@dev.tdt.de --- arch/mips/pci/pci-lantiq.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/mips/pci/pci-lantiq.c b/arch/mips/pci/pci-lantiq.c index 68a8cefed420..0844db34022e 100644 --- a/arch/mips/pci/pci-lantiq.c +++ b/arch/mips/pci/pci-lantiq.c @@ -124,14 +124,14 @@ static int ltq_pci_startup(struct platform_device *pdev) clk_disable(clk_external);
/* setup reset gpio used by pci */ - reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", - GPIOD_OUT_LOW); + reset_gpio = devm_gpiod_get_optional(&pdev->dev, "reset", GPIOD_ASIS); error = PTR_ERR_OR_ZERO(reset_gpio); if (error) { dev_err(&pdev->dev, "failed to request gpio: %d\n", error); return error; } gpiod_set_consumer_name(reset_gpio, "pci_reset"); + gpiod_direction_output(reset_gpio, 1);
/* enable auto-switching between PCI and EBU */ ltq_pci_w32(0xa, PCI_CR_CLK_CTRL); @@ -194,10 +194,10 @@ static int ltq_pci_startup(struct platform_device *pdev)
/* toggle reset pin */ if (reset_gpio) { - gpiod_set_value_cansleep(reset_gpio, 1); + gpiod_set_value_cansleep(reset_gpio, 0); wmb(); mdelay(1); - gpiod_set_value_cansleep(reset_gpio, 0); + gpiod_set_value_cansleep(reset_gpio, 1); } return 0; }