[PATCH 03/11] PCI: tegra194: Fix Endpoint PERST# IRQ suspend race

[Manikanta Maddireddy]

Endpoint mode disables the PERST# IRQ during system suspend when the
link is down.  The old code checked ep_state before disabling the IRQ,
so the host could deassert PERST# in that window and the IRQ thread
could move the endpoint to EP_STATE_ENABLED after the suspend check had
already passed.

Disable the PERST# IRQ before checking ep_state and re-enable it
immediately when suspend is rejected.  Pair the successful suspend
disable with the normal resume callback, because PM rollback after
another device aborts suspend invokes .resume, not .resume_early.

Wrap the PM ops pointer with pm_sleep_ptr() so the callbacks are used
only when system sleep is enabled.

Fixes: c76f8eae7d46 ("PCI: tegra194: Allow system suspend when the Endpoint link is not up")
Link: https://lore.kernel.org/r/20260324190755.1094879-10-mmaddireddy@xxxxxxxxxx
Signed-off-by: Manikanta Maddireddy <mmaddireddy@xxxxxxxxxx>
---
 drivers/pci/controller/dwc/pcie-tegra194.c | 33 ++++++++++++++--------
 1 file changed, 21 insertions(+), 12 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 810695d8e5c8..b91073a6305a 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -2374,19 +2374,29 @@ static int tegra_pcie_dw_suspend(struct device *dev)
 {
 	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
 
-	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
-		if (pcie->ep_state == EP_STATE_ENABLED) {
-			dev_err(dev, "Tegra PCIe is in EP mode, suspend not allowed\n");
-			return -EPERM;
-		}
-
-		disable_irq(pcie->pex_rst_irq);
+	if (pcie->of_data->mode != DW_PCIE_EP_TYPE)
 		return 0;
+
+	disable_irq(pcie->pex_rst_irq);
+	if (pcie->ep_state == EP_STATE_ENABLED) {
+		enable_irq(pcie->pex_rst_irq);
+		dev_err(dev, "Tegra PCIe is in EP mode, suspend not allowed\n");
+		return -EPERM;
 	}
 
 	return 0;
 }
 
+static int tegra_pcie_dw_resume(struct device *dev)
+{
+	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
+
+	if (pcie->of_data->mode == DW_PCIE_EP_TYPE)
+		enable_irq(pcie->pex_rst_irq);
+
+	return 0;
+}
+
 static int tegra_pcie_dw_suspend_late(struct device *dev)
 {
 	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
@@ -2462,10 +2472,8 @@ static int tegra_pcie_dw_resume_early(struct device *dev)
 	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
 	u32 val;
 
-	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
-		enable_irq(pcie->pex_rst_irq);
+	if (pcie->of_data->mode == DW_PCIE_EP_TYPE)
 		return 0;
-	}
 
 	if (!pcie->link_state)
 		return 0;
@@ -2569,10 +2577,11 @@ static const struct of_device_id tegra_pcie_dw_of_match[] = {
 
 static const struct dev_pm_ops tegra_pcie_dw_pm_ops = {
 	.suspend = tegra_pcie_dw_suspend,
+	.resume = tegra_pcie_dw_resume,
 	.suspend_late = tegra_pcie_dw_suspend_late,
+	.resume_early = tegra_pcie_dw_resume_early,
 	.suspend_noirq = tegra_pcie_dw_suspend_noirq,
 	.resume_noirq = tegra_pcie_dw_resume_noirq,
-	.resume_early = tegra_pcie_dw_resume_early,
 };
 
 static struct platform_driver tegra_pcie_dw_driver = {
@@ -2581,7 +2590,7 @@ static struct platform_driver tegra_pcie_dw_driver = {
 	.shutdown = tegra_pcie_dw_shutdown,
 	.driver = {
 		.name	= "tegra194-pcie",
-		.pm = &tegra_pcie_dw_pm_ops,
+		.pm = pm_sleep_ptr(&tegra_pcie_dw_pm_ops),
 		.of_match_table = tegra_pcie_dw_of_match,
 	},
 };
-- 
2.34.1