PCI: imx: Do not hang if REFCLK is missing

Fails the probe with ENODEV when the REFCLK is missing and the PCIe PLL
cannot be locked. Without this change the driver just hang during
probe, completing freezing the system.

Upstream-Status: Pending
This is required to solve a specific issue we have on Colibri-iMX8X,
in which we have the PCIe node enabled for non Wi-Fi variant
and the PCIe REFCLK generator is not assembled.

Upstream driver does not support i.MX8QXP at the moment,
therefore there is nothing we can upstream.

Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>

1 files changed, 26 insertions, 16 deletions

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index ec654c499b1a..ef6492f3fbbb 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -841,7 +841,7 @@ static void imx7d_pcie_wait_for_phy_pll_lock(struct imx6_pcie *imx6_pcie)
 		dev_err(dev, "PCIe PLL lock timeout\n");
 }
 
-static void imx8_pcie_wait_for_phy_pll_lock(struct imx6_pcie *imx6_pcie)
+static int imx8_pcie_wait_for_phy_pll_lock(struct imx6_pcie *imx6_pcie)
 {
 	u32 val, offset = 0, cond = 0;
 	int ret = 0;
@@ -905,10 +905,13 @@ static void imx8_pcie_wait_for_phy_pll_lock(struct imx6_pcie *imx6_pcie)
 	default:
 		break;
 	}
-	if (ret)
+	if (ret) {
 		dev_err(dev, "PCIe PLL lock timeout\n");
-	else
-		dev_info(dev, "PCIe PLL is locked.\n");
+		return ret;
+	}
+
+	dev_info(dev, "PCIe PLL is locked.\n");
+	return 0;
 }
 
 static void imx6_pcie_clk_enable(struct imx6_pcie *imx6_pcie)
@@ -1152,7 +1155,7 @@ static void imx6_pcie_set_l1_latency(struct imx6_pcie *imx6_pcie)
 	}
 }
 
-static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
+static int imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
 {
 	struct dw_pcie *pci = imx6_pcie->pci;
 	struct device *dev = pci->dev;
@@ -1164,7 +1167,7 @@ static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
 		if (ret) {
 			dev_err(dev, "failed to enable vpcie regulator: %d\n",
 				ret);
-			return;
+			return 0;
 		}
 	}
 
@@ -1212,7 +1215,9 @@ static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
 			dev_err(dev, "ERROR PM_REQ_CORE_RST is still set.\n");
 
 		/* wait for phy pll lock firstly. */
-		imx8_pcie_wait_for_phy_pll_lock(imx6_pcie);
+		ret = imx8_pcie_wait_for_phy_pll_lock(imx6_pcie);
+		if (ret)
+			return ret;
 		break;
 	case IMX8MQ:
 	case IMX8MM:
@@ -1348,7 +1353,7 @@ static void imx6_pcie_deassert_core_reset(struct imx6_pcie *imx6_pcie)
 		msleep(100);
 	}
 
-	return;
+	return 0;
 }
 
 static void imx6_pcie_configure_type(struct imx6_pcie *imx6_pcie)
@@ -2294,7 +2299,9 @@ static int imx6_pcie_resume_noirq(struct device *dev)
 	} else {
 		imx6_pcie_assert_core_reset(imx6_pcie);
 		imx6_pcie_init_phy(imx6_pcie);
-		imx6_pcie_deassert_core_reset(imx6_pcie);
+		ret = imx6_pcie_deassert_core_reset(imx6_pcie);
+		if (ret)
+			return ret;
 		dw_pcie_setup_rc(pp);
 		pci_imx_set_msi_en(pp);
 
@@ -2660,7 +2667,9 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 		gpio_set_value_cansleep(imx6_pcie->dis_gpio, 1);
 	imx6_pcie_assert_core_reset(imx6_pcie);
 	imx6_pcie_init_phy(imx6_pcie);
-	imx6_pcie_deassert_core_reset(imx6_pcie);
+	ret = imx6_pcie_deassert_core_reset(imx6_pcie);
+	if (ret)
+		goto err_ret_reg;
 	imx6_setup_phy_mpll(imx6_pcie);
 
 	switch (imx6_pcie->drvdata->mode) {
@@ -2668,7 +2677,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 		/* add attributes for bus freq */
 		ret = sysfs_create_group(&pdev->dev.kobj, &imx_pcie_attrgroup);
 		if (ret)
-			goto err_ret;
+			goto err_ret_reg;
 
 		ret = dw_pcie_host_init(&pci->pp);
 		if (ret < 0) {
@@ -2677,8 +2686,7 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 				dev_info(dev, "To do the compliance tests.\n");
 				ret = 0;
 			} else {
-				imx6_pcie_detach_pd(dev);
-				return ret;
+				goto err_ret_reg;
 			}
 		}
 
@@ -2687,20 +2695,22 @@ static int imx6_pcie_probe(struct platform_device *pdev)
 	case DW_PCIE_EP_TYPE:
 		if (!IS_ENABLED(CONFIG_PCI_IMX6_EP)) {
 			ret = -ENODEV;
-			goto err_ret;
+			goto err_ret_reg;
 		}
 
 		ret = imx_add_pcie_ep(imx6_pcie, pdev);
 		if (ret < 0)
-			goto err_ret;
+			goto err_ret_reg;
 		break;
 	default:
 		dev_err(dev, "INVALID device type.\n");
-		goto err_ret;
+		goto err_ret_reg;
 	}
 
 	return 0;
 
+err_ret_reg:
+	regulator_disable(imx6_pcie->epdev_on);
 err_ret:
 	imx6_pcie_detach_pd(dev);
 	return ret;