linux-kernel - [PATCH v2 1/5] PCI: imx6: Don't poll LTSSM state of i.MX6QP PCIe in PM operations

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Message-Id: <20250618024116.3704579-2-hongxing.zhu@nxp.com>
Date: Wed, 18 Jun 2025 10:41:12 +0800
From: Richard Zhu <hongxing.zhu@....com>
To: frank.li@....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>
Subject: [PATCH v2 1/5] PCI: imx6: Don't poll LTSSM state of i.MX6QP PCIe in PM operations

Refer to PCIe r6.0, sec 5.2, fig 5-1 Link Power Management State Flow
Diagram. Both L0 and L2/L3 Ready 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, whatever the LTSSM state is in L2 or L3 after
a recommended 10ms max wait refer to PCIe r6.0, sec 5.3.3.2.1 PME
Synchronization.

The LTSSM states of i.MX6QP PCIe is inaccessible after the PME_Turn_Off
is kicked off. To handle this case, don't poll L2 state and add one max
10ms delay if QUIRK_NOL2POLL_IN_PM flag is existing in suspend.

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 5a38cfaf989b..8b7daaf36fef 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -125,6 +125,7 @@ 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;
@@ -1759,6 +1760,7 @@ 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);
@@ -1837,6 +1839,7 @@ 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