quoted

quoted

+
+       if (ret)
+               return ret;
+
+       state = readl(&cdns->otg_regs->sts);
+       if (OTGSTS_OTG_NRDY(state) != 0) {
+               dev_err(cdns->dev, "Cadence USB3 OTG device not ready\n");
+               return -ENODEV;
+       }
+
+       ret = cdns3_drd_update_mode(cdns);
+

Calling this function, it is timeout for waiting OTGSTS_XHCI_READY at otgsts,
do you know possible reasons?  After commenting out this function, my
xHCI function
works.

Pawel, since OTG compliance (Known as HNP/SRP)  has not been used
widely, Linux kernel does not
maintain it from some time ago (maybe 1-2 years). In software design,
we do not need to consider it from
hardware point, eg, kinds of OTG timer. For dual-role switch on the
fly,  through /sys is enough.

Through the debug, we find it needs to wait 1s after setting de-select
the host or gadget before request
XHCI at otg_regs->cmd, and enable fast simulate can reduce delay to
2-3ms. Would you please help
to check with your hardware team this behavior. With below changes, I
can get OTGSTS_XHCI_READY at otgsts.

@@ -141,6 +143,7 @@ static int cdns3_drd_switch_host(struct cdns3 *cdns, int on)
               writel(OTGCMD_HOST_BUS_DROP | OTGCMD_DEV_BUS_DROP |
                      OTGCMD_DEV_POWER_OFF | OTGCMD_HOST_POWER_OFF,
                      &cdns->otg_regs->cmd);
+               usleep_range(3000, 4000);
       }

       return 0;

@@ -178,6 +181,7 @@ static int cdns3_drd_switch_gadget(struct cdns3

*cdns, int on)
               writel(OTGCMD_HOST_BUS_DROP | OTGCMD_DEV_BUS_DROP |
                      OTGCMD_DEV_POWER_OFF | OTGCMD_HOST_POWER_OFF,
                      &cdns->otg_regs->cmd);
+               usleep_range(3000, 4000);
       }

@@ -299,6 +306,7 @@ int cdns3_drd_init(struct cdns3 *cdns)
               cdns->version  = CDNS3_CONTROLLER_V0;
               cdns->otg_v1_regs = NULL;
               cdns->otg_regs = regs;
+               writel(0x1, &cdns->otg_v0_regs->simulate);
               dev_info(cdns->dev, "DRD version v0 (%08x)\n",
                        readl(&cdns->otg_v0_regs->version));
       } else {