linux-kernel - [PATCH v6 3/4] PCI: dwc: Skip PME_Turn_Off message if there is no endpoint connected

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Message-Id: <20250924072324.3046687-4-hongxing.zhu@nxp.com>
Date: Wed, 24 Sep 2025 15:23:23 +0800
From: Richard Zhu <hongxing.zhu@....com>
To: frank.li@....com,
	jingoohan1@...il.com,
	l.stach@...gutronix.de,
	lpieralisi@...nel.org,
	kwilczynski@...nel.org,
	mani@...nel.org,
	robh@...nel.org,
	bhelgaas@...gle.com,
	shawnguo@...nel.org,
	s.hauer@...gutronix.de,
	kernel@...gutronix.de,
	festevam@...il.com
Cc: linux-pci@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	imx@...ts.linux.dev,
	linux-kernel@...r.kernel.org,
	Richard Zhu <hongxing.zhu@....com>,
	stable@...r.kernel.org,
	Frank Li <Frank.Li@....com>
Subject: [PATCH v6 3/4] PCI: dwc: Skip PME_Turn_Off message if there is no endpoint connected

A chip freeze is observed on i.MX7D when PCIe RC kicks off the PM_PME
message and no any devices are connected on the port.

To workaroud such kind of issue, skip PME_Turn_Off message if there is
no endpoint connected.

Cc: stable@...r.kernel.org
Fixes: 4774faf854f5 ("PCI: dwc: Implement generic suspend/resume functionality")
Fixes: a528d1a72597 ("PCI: imx6: Use DWC common suspend resume method")
Signed-off-by: Richard Zhu <hongxing.zhu@....com>
Reviewed-by: Frank Li <Frank.Li@....com>
---
 drivers/pci/controller/dwc/pcie-designware-host.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 57a1ba08c427..b303a74b0fd7 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -1008,12 +1008,15 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 	u32 val;
 	int ret;
 
-	if (pci->pp.ops->pme_turn_off) {
-		pci->pp.ops->pme_turn_off(&pci->pp);
-	} else {
-		ret = dw_pcie_pme_turn_off(pci);
-		if (ret)
-			return ret;
+	/* Skip PME_Turn_Off message if there is no endpoint connected */
+	if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_WAIT) {
+		if (pci->pp.ops->pme_turn_off) {
+			pci->pp.ops->pme_turn_off(&pci->pp);
+		} else {
+			ret = dw_pcie_pme_turn_off(pci);
+			if (ret)
+				return ret;
+		}
 	}
 
 	if (dwc_quirk(pci, QUIRK_NOL2POLL_IN_PM)) {
-- 
2.37.1