linux-kernel - [PATCH v1 2/4] PCI: dwc: Add quirk to fix hang issue when send out PME_Turn

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Message-Id: <20250408065221.1941928-3-hongxing.zhu@nxp.com>
Date: Tue,  8 Apr 2025 14:52:19 +0800
From: Richard Zhu <hongxing.zhu@....com>
To: jingoohan1@...il.com,
	frank.li@....com,
	l.stach@...gutronix.de,
	lpieralisi@...nel.org,
	kw@...ux.com,
	manivannan.sadhasivam@...aro.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>
Subject: [PATCH v1 2/4] PCI: dwc: Add quirk to fix hang issue when send out PME_Turn_Off Msg TLP

When no endpoint is connected on i.MX7D PCIe, chip would be freeze when do
the dummy write in dw_pcie_pme_turn_off() to issue a PME_Turn_Off Msg TLP.

Add one quirk to issue the PME_Turn_Off only when link is up to avoid
this problem on the PME_Turn_Off handshake broken platform, for example
the i.MX7D.

Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
 .../pci/controller/dwc/pcie-designware-host.c    | 16 +++++++++++-----
 drivers/pci/controller/dwc/pcie-designware.h     |  1 +
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-host.c b/drivers/pci/controller/dwc/pcie-designware-host.c
index 0817df5b8a59..a62bf7e0ade8 100644
--- a/drivers/pci/controller/dwc/pcie-designware-host.c
+++ b/drivers/pci/controller/dwc/pcie-designware-host.c
@@ -956,12 +956,18 @@ int dw_pcie_suspend_noirq(struct dw_pcie *pci)
 	if (dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKCTL) & PCI_EXP_LNKCTL_ASPM_L1)
 		return 0;
 
-	if (pci->pp.ops->pme_turn_off) {
-		pci->pp.ops->pme_turn_off(&pci->pp);
+	if (dw_pcie_get_ltssm(pci) <= DW_PCIE_LTSSM_DETECT_WAIT &&
+	    dwc_check_quirk(pci, QUIRK_NOLINK_NOPME)) {
+		/* Don't send the PME_TURN_OFF when link is down. */
+		;
 	} else {
-		ret = dw_pcie_pme_turn_off(pci);
-		if (ret)
-			return 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;
+		}
 	}
 
 	if (!dwc_check_quirk(pci, QUIRK_NOL2POLL_IN_PM)) {
diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
index 05fe654d7761..d752af660e95 100644
--- a/drivers/pci/controller/dwc/pcie-designware.h
+++ b/drivers/pci/controller/dwc/pcie-designware.h
@@ -283,6 +283,7 @@
 #define DMA_LLP_MEM_SIZE		PAGE_SIZE
 
 #define QUIRK_NOL2POLL_IN_PM		BIT(0)
+#define QUIRK_NOLINK_NOPME		BIT(1)
 #define dwc_check_quirk(pci, val)	(pci->quirk_flag & val)
 
 struct dw_pcie;
-- 
2.37.1