PCI: tegra194: Don't allow suspend when Tegra PCIe is in EP mode

When Tegra PCIe is in endpoint mode it should be available for root port.
PCIe link up by root port fails if it is in suspend state. So, don't allow
Tegra to suspend when endpoint mode is enabled.

Link: https://lore.kernel.org/r/20210623100525.19944-5-omp@nvidia.com
Signed-off-by: Om Prakash Singh <omp@nvidia.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Vidya Sagar <vidyas@nvidia.com>

drivers/pci/controller/dwc/pcie-tegra194.c

@@ -2246,6 +2246,11 @@ static int tegra_pcie_dw_resume_early(struct device *dev)
 	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
 	u32 val;
 
+	if (pcie->mode == DW_PCIE_EP_TYPE) {
+		dev_err(dev, "Suspend is not supported in EP mode");
+		return -ENOTSUPP;
+	}
+
 	if (!pcie->link_state)
 		return 0;