Some designs implement reset GPIO via a GPIO expander connected to a
peripheral bus. One such example would be i.MX7 Sabre board where said
GPIO is provided by SPI shift register connected to a bitbanged SPI
bus. In order to support such designs allow reset GPIO request to defer
probing of the driver.

Cc: yurov...@gmail.com
Cc: Lucas Stach <l.st...@pengutronix.de>
Cc: Bjorn Helgaas <bhelg...@google.com>
Cc: linux-arm-ker...@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
---
 drivers/pci/host/pci-imx6.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index 50a1291..3ef8093 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -611,7 +611,7 @@ static int __init imx6_add_pcie_port(struct imx6_pcie 
*imx6_pcie,
        return 0;
 }
 
-static int __init imx6_pcie_probe(struct platform_device *pdev)
+static int imx6_pcie_probe(struct platform_device *pdev)
 {
        struct device *dev = &pdev->dev;
        struct imx6_pcie *imx6_pcie;
@@ -653,6 +653,8 @@ static int __init imx6_pcie_probe(struct platform_device 
*pdev)
                        dev_err(dev, "unable to get reset gpio\n");
                        return ret;
                }
+       } else if (imx6_pcie->reset_gpio == -EPROBE_DEFER) {
+               return imx6_pcie->reset_gpio;
        }
 
        /* Fetch clocks */
@@ -746,11 +748,12 @@ static struct platform_driver imx6_pcie_driver = {
                .name   = "imx6q-pcie",
                .of_match_table = imx6_pcie_of_match,
        },
+       .probe    = imx6_pcie_probe,
        .shutdown = imx6_pcie_shutdown,
 };
 
 static int __init imx6_pcie_init(void)
 {
-       return platform_driver_probe(&imx6_pcie_driver, imx6_pcie_probe);
+       return platform_driver_register(&imx6_pcie_driver);
 }
 device_initcall(imx6_pcie_init);
-- 
2.9.3

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