linux-kernel - [PATCH v10 6/7] PCI: imx6: Mark the link down as none fatal error

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Date:   Mon, 13 Jun 2022 16:55:37 +0800
From:   Richard Zhu <hongxing.zhu@....com>
To:     l.stach@...gutronix.de, bhelgaas@...gle.com, robh+dt@...nel.org,
        broonie@...nel.org, lorenzo.pieralisi@....com, festevam@...il.com,
        francesco.dolcini@...adex.com
Cc:     hongxing.zhu@....com, linux-pci@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        kernel@...gutronix.de, linux-imx@....com
Subject: [PATCH v10 6/7] PCI: imx6: Mark the link down as none fatal error

let the driver probe successfully, return zero in imx6_pcie_start_link()
when PCIe link is down.

Because i.MX PCIe doesn't support hot-plug feature.
In this link down scenario, only start the PCIe link training in resume
when the link is up before system suspend to avoid the long latency in
the link training period.

Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index c02748393aac..ac6ec2d691a0 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -67,6 +67,7 @@ struct imx6_pcie {
 	struct dw_pcie		*pci;
 	int			reset_gpio;
 	bool			gpio_active_high;
+	bool			link_is_up;
 	struct clk		*pcie_bus;
 	struct clk		*pcie_phy;
 	struct clk		*pcie_inbound_axi;
@@ -845,7 +846,9 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
 	/* Start LTSSM. */
 	imx6_pcie_ltssm_enable(dev);
 
-	dw_pcie_wait_for_link(pci);
+	ret = dw_pcie_wait_for_link(pci);
+	if (ret)
+		goto err_reset_phy;
 
 	if (pci->link_gen == 2) {
 		/* Allow Gen2 mode after the link is up. */
@@ -881,11 +884,14 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
 		}
 
 		/* Make sure link training is finished as well! */
-		dw_pcie_wait_for_link(pci);
+		ret = dw_pcie_wait_for_link(pci);
+		if (ret)
+			goto err_reset_phy;
 	} else {
 		dev_info(dev, "Link: Gen2 disabled\n");
 	}
 
+	imx6_pcie->link_is_up = true;
 	tmp = dw_pcie_readw_dbi(pci, offset + PCI_EXP_LNKSTA);
 	dev_info(dev, "Link up, Gen%i\n", tmp & PCI_EXP_LNKSTA_CLS);
 	return 0;
@@ -895,7 +901,7 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
 		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
 		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
 	imx6_pcie_reset_phy(imx6_pcie);
-	return ret;
+	return 0;
 }
 
 static int imx6_pcie_host_init(struct pcie_port *pp)
@@ -1022,10 +1028,8 @@ static int imx6_pcie_resume_noirq(struct device *dev)
 	imx6_pcie_init_phy(imx6_pcie);
 	imx6_pcie_deassert_core_reset(imx6_pcie);
 	dw_pcie_setup_rc(pp);
-
-	ret = imx6_pcie_start_link(imx6_pcie->pci);
-	if (ret < 0)
-		dev_info(dev, "pcie link is down after resume.\n");
+	if (imx6_pcie->link_is_up)
+		imx6_pcie_start_link(imx6_pcie->pci);
 
 	return 0;
 }
-- 
2.25.1