linux-kernel - [PATCH v12 11/13] PCI: imx6: Reduce resume time by only starting link if it was up before suspend

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Date:   Wed, 15 Jun 2022 18:15:49 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Richard Zhu <hongxing.zhu@....com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Fabio Estevam <festevam@...il.com>,
        Francesco Dolcini <francesco.dolcini@...adex.com>
Cc:     linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kernel@...gutronix.de,
        linux-imx@....com, Bjorn Helgaas <bhelgaas@...gle.com>
Subject: [PATCH v12 11/13] PCI: imx6: Reduce resume time by only starting link if it was up before suspend

From: Richard Zhu <hongxing.zhu@....com>

Because i.MX PCIe doesn't support hot-plug feature.  In the 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.

[bhelgaas: drop now-unused "ret"]
Link: https://lore.kernel.org/r/1655189942-12678-8-git-send-email-hongxing.zhu@nxp.com
Signed-off-by: Richard Zhu <hongxing.zhu@....com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 7d3592540b8a..b6e5420d67b6 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;
@@ -900,6 +901,7 @@ static int imx6_pcie_start_link(struct dw_pcie *pci)
 		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;
@@ -1025,7 +1027,6 @@ static int imx6_pcie_suspend_noirq(struct device *dev)
 
 static int imx6_pcie_resume_noirq(struct device *dev)
 {
-	int ret;
 	struct imx6_pcie *imx6_pcie = dev_get_drvdata(dev);
 	struct pcie_port *pp = &imx6_pcie->pci->pp;
 
@@ -1036,10 +1037,8 @@ 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