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From:   Richard Zhu <hongxing.zhu@nxp.com>
To:     l.stach@pengutronix.de, bhelgaas@google.com, robh+dt@kernel.org,
        broonie@kernel.org, lorenzo.pieralisi@arm.com, festevam@gmail.com,
        francesco.dolcini@toradex.com
Cc:     hongxing.zhu@nxp.com, linux-pci@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        kernel@pengutronix.de, linux-imx@nxp.com
Subject: [PATCH v13 13/15] PCI: imx6: Reduce resume time by only starting link if it was up before suspend
Date:   Fri, 17 Jun 2022 18:31:12 +0800
Message-Id: <1655461874-16908-14-git-send-email-hongxing.zhu@nxp.com>
In-Reply-To: <1655461874-16908-1-git-send-email-hongxing.zhu@nxp.com>
References: <1655461874-16908-1-git-send-email-hongxing.zhu@nxp.com>
Precedence: bulk

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.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index e236f824c808..abce427f5d3f 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;
@@ -881,6 +882,7 @@ 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;
@@ -1032,9 +1034,8 @@ static int imx6_pcie_resume_noirq(struct device *dev)
 		return ret;
 	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