linux-kernel - [PATCH v15 13/17] PCI: imx6: Reduce resume time by only starting link if it was up before suspend

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Message-Id: <1657783869-19194-14-git-send-email-hongxing.zhu@nxp.com>
Date:   Thu, 14 Jul 2022 15:31:05 +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 v15 13/17] PCI: imx6: Reduce resume time by only starting link if it was up before suspend

i.MX PCIe doesn't support hotplug. During resume, only start PCIe link
training when the link was up before system suspend to avoid the long
latency in the link training period.

[bhelgaas: imx6_pcie_start_link() return value check removal moved to
previous patch, pointed out by Lucas Stach <l.stach@...gutronix.de>]
Link: https://lore.kernel.org/r/1656645935-1370-14-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 | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 3ac4f2aa91c5..ad0933c3dc70 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;
@@ -881,11 +882,13 @@ 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;
 
 err_reset_phy:
+	imx6_pcie->link_is_up = false;
 	dev_dbg(dev, "PHY DEBUG_R0=0x%08x DEBUG_R1=0x%08x\n",
 		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG0),
 		dw_pcie_readl_dbi(pci, PCIE_PORT_DEBUG1));
@@ -1032,7 +1035,9 @@ static int imx6_pcie_resume_noirq(struct device *dev)
 		return ret;
 	dw_pcie_setup_rc(pp);
 
-	imx6_pcie_start_link(imx6_pcie->pci);
+	if (imx6_pcie->link_is_up)
+		imx6_pcie_start_link(imx6_pcie->pci);
+
 	return 0;
 }
 #endif
-- 
2.25.1