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

[Richard Zhu <hongxing.zhu@nxp.com>]

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@pengutronix.de>]
Link: https://lore.kernel.org/r/1656645935-1370-14-git-send-email-hongxing.zhu@nxp.com
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, 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