Merge branch 'pci/controller/imx6'

- Fix suspend/resume support on i.MX6QDL, which has a hardware erratum that
  prevents use of L2 (Stefan Eichenberger)

* pci/controller/imx6:
  PCI: imx6: Fix suspend/resume support on i.MX6QDL

Author: bjorn-helgaas

drivers/pci/controller/dwc/pci-imx6.c

@@ -82,6 +82,11 @@ enum imx_pcie_variants {
 #define IMX_PCIE_FLAG_HAS_SERDES		BIT(6)
 #define IMX_PCIE_FLAG_SUPPORT_64BIT		BIT(7)
 #define IMX_PCIE_FLAG_CPU_ADDR_FIXUP		BIT(8)
+/*
+ * Because of ERR005723 (PCIe does not support L2 power down) we need to
+ * workaround suspend resume on some devices which are affected by this errata.
+ */
+#define IMX_PCIE_FLAG_BROKEN_SUSPEND		BIT(9)
 
 #define imx_check_flag(pci, val)	(pci->drvdata->flags & val)
 
@@ -1237,9 +1242,19 @@ static int imx_pcie_suspend_noirq(struct device *dev)
 		return 0;
 
 	imx_pcie_msi_save_restore(imx_pcie, true);
-	imx_pcie_pm_turnoff(imx_pcie);
-	imx_pcie_stop_link(imx_pcie->pci);
-	imx_pcie_host_exit(pp);
+	if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_BROKEN_SUSPEND)) {
+		/*
+		 * The minimum for a workaround would be to set PERST# and to
+		 * set the PCIE_TEST_PD flag. However, we can also disable the
+		 * clock which saves some power.
+		 */
+		imx_pcie_assert_core_reset(imx_pcie);
+		imx_pcie->drvdata->enable_ref_clk(imx_pcie, false);
+	} else {
+		imx_pcie_pm_turnoff(imx_pcie);
+		imx_pcie_stop_link(imx_pcie->pci);
+		imx_pcie_host_exit(pp);
+	}
 
 	return 0;
 }
@@ -1253,14 +1268,32 @@ static int imx_pcie_resume_noirq(struct device *dev)
 	if (!(imx_pcie->drvdata->flags & IMX_PCIE_FLAG_SUPPORTS_SUSPEND))
 		return 0;
 
-	ret = imx_pcie_host_init(pp);
-	if (ret)
-		return ret;
-	imx_pcie_msi_save_restore(imx_pcie, false);
-	dw_pcie_setup_rc(pp);
+	if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_BROKEN_SUSPEND)) {
+		ret = imx_pcie->drvdata->enable_ref_clk(imx_pcie, true);
+		if (ret)
+			return ret;
+		ret = imx_pcie_deassert_core_reset(imx_pcie);
+		if (ret)
+			return ret;
+		/*
+		 * Using PCIE_TEST_PD seems to disable MSI and powers down the
+		 * root complex. This is why we have to setup the rc again and
+		 * why we have to restore the MSI register.
+		 */
+		ret = dw_pcie_setup_rc(&imx_pcie->pci->pp);
+		if (ret)
+			return ret;
+		imx_pcie_msi_save_restore(imx_pcie, false);
+	} else {
+		ret = imx_pcie_host_init(pp);
+		if (ret)
+			return ret;
+		imx_pcie_msi_save_restore(imx_pcie, false);
+		dw_pcie_setup_rc(pp);
 
-	if (imx_pcie->link_is_up)
-		imx_pcie_start_link(imx_pcie->pci);
+		if (imx_pcie->link_is_up)
+			imx_pcie_start_link(imx_pcie->pci);
+	}
 
 	return 0;
 }
@@ -1485,7 +1518,9 @@ static const struct imx_pcie_drvdata drvdata[] = {
 	[IMX6Q] = {
 		.variant = IMX6Q,
 		.flags = IMX_PCIE_FLAG_IMX_PHY |
-			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE,
+			 IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+			 IMX_PCIE_FLAG_BROKEN_SUSPEND |
+			 IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
 		.dbi_length = 0x200,
 		.gpr = "fsl,imx6q-iomuxc-gpr",
 		.clk_names = imx6q_clks,