linux-kernel - [PATCH v1 3/4] PCI: imx6: Fix i.MX6QP PCIe hang issue in L2 poll of suspend

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Message-Id: <20250408065221.1941928-4-hongxing.zhu@nxp.com>
Date: Tue,  8 Apr 2025 14:52:20 +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 3/4] PCI: imx6: Fix i.MX6QP PCIe hang issue in L2 poll of suspend

During suspend/resume, i.MX6QP PCIe is hang in L2 poll when one endpoint
device is connected, for example the Intel e1000e network card.

Refer to Figure5-1 Link Power Management State Flow Diagram of PCI
Express Base Spec Rev6.0. L0 can be transferred to LDn directly.

It's harmless to let dw_pcie_suspend_noirq() proceed suspend after the
PME_Turn_Off is sent out, whateve the ltssm state is in L2 or L3 on some
PME_Turn_Off handshake broken platforms.

To fix this issue, add one quirk to remove the L2 entry poll and let
dw_pcie_suspend_noirq() proceed directly after PME_Turn_Off is sent out.

Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 5f267dd261b5..aade80010cbe 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -116,6 +116,7 @@ struct imx_pcie_drvdata {
 	enum imx_pcie_variants variant;
 	enum dw_pcie_device_mode mode;
 	u32 flags;
+	u32 quirk;
 	int dbi_length;
 	const char *gpr;
 	const u32 ltssm_off;
@@ -1614,6 +1615,7 @@ static int imx_pcie_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	pci->quirk_flag = imx_pcie->drvdata->quirk;
 	pci->use_parent_dt_ranges = true;
 	if (imx_pcie->drvdata->mode == DW_PCIE_EP_TYPE) {
 		ret = imx_add_pcie_ep(imx_pcie, pdev);
@@ -1692,6 +1694,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
 		.enable_ref_clk = imx6q_pcie_enable_ref_clk,
 		.core_reset = imx6qp_pcie_core_reset,
 		.ops = &imx_pcie_host_ops,
+		.quirk = QUIRK_NOL2POLL_IN_PM,
 	},
 	[IMX7D] = {
 		.variant = IMX7D,
-- 
2.37.1