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author | Petr Štetiar <ynezz@true.cz> | 2016-04-19 19:42:07 -0500 |
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committer | Bjorn Helgaas <bhelgaas@google.com> | 2016-04-19 19:42:07 -0500 |
commit | 3ea8529acc30467331b7b1f5da6cf668fac091c7 (patch) | |
tree | 2d08f8d8e392a3badf9e25e1f78932498b0c3d16 /drivers/pci | |
parent | 4f6926e9fdf94208dc37da0cd17835328fa4dbba (diff) | |
download | linux-3ea8529acc30467331b7b1f5da6cf668fac091c7.tar.gz linux-3ea8529acc30467331b7b1f5da6cf668fac091c7.tar.bz2 linux-3ea8529acc30467331b7b1f5da6cf668fac091c7.zip |
PCI: imx6: Add reset-gpio-active-high boolean property to DT
Currently the reset-gpio DT property which controls the PCI bus device
reset signal defaults to active-low reset sequence (L=reset state,
H=operation state) plus the code in reset function isn't GPIO polarity
aware - it doesn't matter if the defined reset-gpio is active-low or
active-high, it will always result into active-low reset sequence.
I've tried to fix it properly and change the reset-gpio reset sequence to
be polarity-aware, but this patch has been accepted and then reverted as it
has introduced few backward incompatible issues:
1. Some DTBs, for example, imx6qdl-sabresd, don't define reset-gpio
polarity correctly:
reset-gpio = <&gpio7 12 0>;
which means that it's defined as active-high, but in reality it's
active-low; thus it wouldn't work without a DTS fix.
2. The logic in the reset function is inverted:
gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0)
msleep(100);
gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1);
so even if some of the i.MX6 boards had reset-gpio polarity defined
correctly in their DTSes, they would stop working.
As we can't break old DTBs, we can't fix them, so we need to introduce this
new DT reset-gpio-active-high boolean property so we can support boards
with active-high reset sequence.
This active-high reset sequence is for example needed on Apalis SoMs, where
GPIO1_IO28, used to PCIe reset is not connected directly to PERST# PCIe
signal, but it's ORed with RESETBMCU coming off the PMIC, and thus is
inverted, active-high.
Tested-by: Tim Harvey <tharvey@gateworks.com> # Gateworks Ventana boards (which have active-low PERST#)
Signed-off-by: Petr Štetiar <ynezz@true.cz>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Diffstat (limited to 'drivers/pci')
-rw-r--r-- | drivers/pci/host/pci-imx6.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c index 7cfe00e34f58..0b8793d908de 100644 --- a/drivers/pci/host/pci-imx6.c +++ b/drivers/pci/host/pci-imx6.c @@ -33,6 +33,7 @@ struct imx6_pcie { int reset_gpio; + bool gpio_active_high; struct clk *pcie_bus; struct clk *pcie_phy; struct clk *pcie_inbound_axi; @@ -348,9 +349,11 @@ static int imx6_pcie_deassert_core_reset(struct pcie_port *pp) /* Some boards don't have PCIe reset GPIO. */ if (gpio_is_valid(imx6_pcie->reset_gpio)) { - gpio_set_value_cansleep(imx6_pcie->reset_gpio, 0); + gpio_set_value_cansleep(imx6_pcie->reset_gpio, + imx6_pcie->gpio_active_high); msleep(100); - gpio_set_value_cansleep(imx6_pcie->reset_gpio, 1); + gpio_set_value_cansleep(imx6_pcie->reset_gpio, + !imx6_pcie->gpio_active_high); } if (imx6_pcie->is_imx6sx) @@ -600,9 +603,14 @@ static int __init imx6_pcie_probe(struct platform_device *pdev) /* Fetch GPIOs */ imx6_pcie->reset_gpio = of_get_named_gpio(np, "reset-gpio", 0); + imx6_pcie->gpio_active_high = of_property_read_bool(np, + "reset-gpio-active-high"); if (gpio_is_valid(imx6_pcie->reset_gpio)) { ret = devm_gpio_request_one(&pdev->dev, imx6_pcie->reset_gpio, - GPIOF_OUT_INIT_LOW, "PCIe reset"); + imx6_pcie->gpio_active_high ? + GPIOF_OUT_INIT_HIGH : + GPIOF_OUT_INIT_LOW, + "PCIe reset"); if (ret) { dev_err(&pdev->dev, "unable to get reset gpio\n"); return ret; |