linux-kernel - [PATCH V3 14/21] PCI: tegra194: Allow system suspend when the Endpoint link is not up

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Date:   Fri, 14 Oct 2022 00:08:47 +0530
From:   Vidya Sagar <vidyas@...dia.com>
To:     <lpieralisi@...nel.org>, <robh@...nel.org>, <kw@...ux.com>,
        <bhelgaas@...gle.com>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <kishon@...com>, <vkoul@...nel.org>,
        <mani@...nel.org>, <Sergey.Semin@...kalelectronics.ru>,
        <ffclaire1224@...il.com>
CC:     <linux-pci@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-phy@...ts.infradead.org>,
        <kthota@...dia.com>, <mmaddireddy@...dia.com>, <vidyas@...dia.com>,
        <sagar.tv@...il.com>
Subject: [PATCH V3 14/21] PCI: tegra194: Allow system suspend when the Endpoint link is not up

Only a Root port initiates the L2 sequence. PCIe link is kept in L2 state
during suspend. If Endpoint mode is enabled and the link is up, the
software cannot proceed with suspend. However, when the PCIe Endpoint
driver is probed, but the PCIe link is not up, Tegra can go into suspend
state. So, allow system to suspend in this case.

Signed-off-by: Vidya Sagar <vidyas@...dia.com>
---
V3:
* This is a new patch in this series

 drivers/pci/controller/dwc/pcie-tegra194.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
index 78ee0f713e71..e6fd713e9868 100644
--- a/drivers/pci/controller/dwc/pcie-tegra194.c
+++ b/drivers/pci/controller/dwc/pcie-tegra194.c
@@ -2425,8 +2425,14 @@ static int tegra_pcie_dw_suspend_late(struct device *dev)
 	u32 val;
 
 	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
-		dev_err(dev, "Failed to Suspend as Tegra PCIe is in EP mode\n");
-		return -EPERM;
+		disable_irq(pcie->pex_rst_irq);
+
+		if (pcie->ep_state == EP_STATE_ENABLED) {
+			dev_err(dev, "Tegra PCIe is in EP mode, suspend not allowed");
+			return -EPERM;
+		} else {
+			return 0;
+		}
 	}
 
 	if (!pcie->link_state && !pcie->slot_pluggable)
@@ -2448,6 +2454,9 @@ static int tegra_pcie_dw_suspend_noirq(struct device *dev)
 {
 	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
 
+	if (pcie->of_data->mode == DW_PCIE_EP_TYPE)
+		return 0;
+
 	if (!pcie->link_state && !pcie->slot_pluggable)
 		return 0;
 
@@ -2463,6 +2472,9 @@ static int tegra_pcie_dw_resume_noirq(struct device *dev)
 	struct tegra_pcie_dw *pcie = dev_get_drvdata(dev);
 	int ret;
 
+	if (pcie->of_data->mode == DW_PCIE_EP_TYPE)
+		return 0;
+
 	if (!pcie->link_state && !pcie->slot_pluggable)
 		return 0;
 
@@ -2495,8 +2507,8 @@ static int tegra_pcie_dw_resume_early(struct device *dev)
 	u32 val;
 
 	if (pcie->of_data->mode == DW_PCIE_EP_TYPE) {
-		dev_err(dev, "Suspend is not supported in EP mode");
-		return -ENOTSUPP;
+		enable_irq(pcie->pex_rst_irq);
+		return 0;
 	}
 
 	if (!pcie->link_state && !pcie->slot_pluggable)
-- 
2.17.1