PCI: imx6: Skip link up workaround for newer platforms

The current link setup procedure has one workaround to detect the devices
behind PCIe switches on some i.MX6 platforms. But this workaround is not
needed on recent i.MX7 platforms. So skip the workaround for platforms that
do not set the flag and start LTSSM directly.

Also, change the flag name from IMX_PCIE_FLAG_IMX_SPEED_CHANGE to
IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND to match the usecase.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
[mani: subject and description rewording]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://patch.msgid.link/20250416081314.3929794-2-hongxing.zhu@nxp.com

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 5f267dd261b51e198352a1f2b1898802548774ea..a4c0714c6468c33ce3638c39be2a1bf55bd0a6fb 100644 (file)
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -91,7 +91,7 @@ enum imx_pcie_variants {
 };
 
 #define IMX_PCIE_FLAG_IMX_PHY                  BIT(0)
-#define IMX_PCIE_FLAG_IMX_SPEED_CHANGE         BIT(1)
+#define IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND  BIT(1)
 #define IMX_PCIE_FLAG_SUPPORTS_SUSPEND         BIT(2)
 #define IMX_PCIE_FLAG_HAS_PHYDRV               BIT(3)
 #define IMX_PCIE_FLAG_HAS_APP_RESET            BIT(4)
@@ -860,6 +860,12 @@ static int imx_pcie_start_link(struct dw_pcie *pci)
        u32 tmp;
        int ret;
 
+       if (!(imx_pcie->drvdata->flags &
+           IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND)) {
+               imx_pcie_ltssm_enable(dev);
+               return 0;
+       }
+
        /*
         * Force Gen1 operation when starting the link.  In case the link is
         * started in Gen2 mode, there is a possibility the devices on the
@@ -896,22 +902,10 @@ static int imx_pcie_start_link(struct dw_pcie *pci)
                dw_pcie_writel_dbi(pci, PCIE_LINK_WIDTH_SPEED_CONTROL, tmp);
                dw_pcie_dbi_ro_wr_dis(pci);
 
-               if (imx_pcie->drvdata->flags &
-                   IMX_PCIE_FLAG_IMX_SPEED_CHANGE) {
-
-                       /*
-                        * On i.MX7, DIRECT_SPEED_CHANGE behaves differently
-                        * from i.MX6 family when no link speed transition
-                        * occurs and we go Gen1 -> yep, Gen1. The difference
-                        * is that, in such case, it will not be cleared by HW
-                        * which will cause the following code to report false
-                        * failure.
-                        */
-                       ret = imx_pcie_wait_for_speed_change(imx_pcie);
-                       if (ret) {
-                               dev_err(dev, "Failed to bring link up!\n");
-                               goto err_reset_phy;
-                       }
+               ret = imx_pcie_wait_for_speed_change(imx_pcie);
+               if (ret) {
+                       dev_err(dev, "Failed to bring link up!\n");
+                       goto err_reset_phy;
                }
 
                /* Make sure link training is finished as well! */
@@ -1649,7 +1643,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
        [IMX6Q] = {
                .variant = IMX6Q,
                .flags = IMX_PCIE_FLAG_IMX_PHY |
-                        IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+                        IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND |
                         IMX_PCIE_FLAG_BROKEN_SUSPEND |
                         IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
                .dbi_length = 0x200,
@@ -1665,7 +1659,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
        [IMX6SX] = {
                .variant = IMX6SX,
                .flags = IMX_PCIE_FLAG_IMX_PHY |
-                        IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+                        IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND |
                         IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
                .gpr = "fsl,imx6q-iomuxc-gpr",
                .ltssm_off = IOMUXC_GPR12,
@@ -1680,7 +1674,7 @@ static const struct imx_pcie_drvdata drvdata[] = {
        [IMX6QP] = {
                .variant = IMX6QP,
                .flags = IMX_PCIE_FLAG_IMX_PHY |
-                        IMX_PCIE_FLAG_IMX_SPEED_CHANGE |
+                        IMX_PCIE_FLAG_SPEED_CHANGE_WORKAROUND |
                         IMX_PCIE_FLAG_SUPPORTS_SUSPEND,
                .dbi_length = 0x200,
                .gpr = "fsl,imx6q-iomuxc-gpr",