PCI: tegra194: Disable PERST# IRQ only in Endpoint mode

[ Upstream commit 40658a3 ]

The PERST# GPIO interrupt is only registered when the controller is
operating in Endpoint mode. In Root Port mode, the PERST# GPIO is
configured as an output to control downstream devices, and no interrupt is
registered for it.

Currently, tegra_pcie_dw_stop_link() unconditionally calls disable_irq()
on pex_rst_irq, which causes issues in Root Port mode where this IRQ is
not registered.

Fix this by only disabling the PERST# IRQ when operating in Endpoint mode,
where the interrupt is actually registered and used to detect PERST#
assertion/deassertion from the host.

Fixes: c57247f ("PCI: tegra: Add support for PCIe endpoint mode in Tegra194")
Signed-off-by: Manikanta Maddireddy <mmaddireddy@nvidia.com>
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
Reviewed-by: Vidya Sagar <vidyas@nvidia.com>
Link: https://patch.msgid.link/20260324190755.1094879-6-mmaddireddy@nvidia.com
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Manikanta Maddireddy

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

@@ -1054,7 +1054,8 @@ static void tegra_pcie_dw_stop_link(struct dw_pcie *pci)
 {
 	struct tegra_pcie_dw *pcie = to_tegra_pcie(pci);
 
-	disable_irq(pcie->pex_rst_irq);
+	if (pcie->of_data->mode == DW_PCIE_EP_TYPE)
+		disable_irq(pcie->pex_rst_irq);
 }
 
 static const struct dw_pcie_ops tegra_dw_pcie_ops = {