[v2,1/1] usb: xhci: do not create and register shared_hcd when USB3.0 is disabled

["Thang Q. Nguyen" <tqnguyen@apm.com>]

From: Tung Nguyen <tunguyen@apm.com>

Currently, hcd->shared_hcd always creates and registers to the usb-core.
If, for some reasons, USB3 downstream port is disabled, no roothub port for
USB3.0 is found. This causes kernel to display an error:
hub 2-0:1.0: config failed, hub doesn't have any ports! (err -19)
This patch checks and registers shared_hcd if USB3.0 downstream
port is available.

Signed-off-by: Tung Nguyen <tunguyen@apm.com>
---
 drivers/usb/host/xhci-plat.c |  9 ++++++---
 drivers/usb/host/xhci.c      | 13 +++++++++++++
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/host/xhci-plat.c b/drivers/usb/host/xhci-plat.c
index 6f03830..bdb3975 100644
--- a/drivers/usb/host/xhci-plat.c
+++ b/drivers/usb/host/xhci-plat.c
@@ -293,9 +293,12 @@ static int xhci_plat_probe(struct platform_device *pdev)
 	if (HCC_MAX_PSA(xhci->hcc_params) >= 4)
 		xhci->shared_hcd->can_do_streams = 1;
 
-	ret = usb_add_hcd(xhci->shared_hcd, irq, IRQF_SHARED);
-	if (ret)
-		goto dealloc_usb2_hcd;
+	/* Just add the shared_hcd when USB3.0 downstream port is available */
+	if (xhci->num_usb3_ports > 0) {
+		ret = usb_add_hcd(xhci->shared_hcd, irq, IRQF_SHARED);
+		if (ret)
+			goto dealloc_usb2_hcd;
+	}
 
 	device_enable_async_suspend(&pdev->dev);
 	pm_runtime_put_noidle(&pdev->dev);
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 1eeb339..9d3b1ab 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -611,6 +611,19 @@ int xhci_run(struct usb_hcd *hcd)
 		if (ret)
 			xhci_free_command(xhci, command);
 	}
+	/*
+	 * In case that the USB3.0 downstream port is not available
+	 * No one triggers to start the xHC which should be done
+	 * before finishing xhci_run
+	 */
+	if (xhci->num_usb3_ports == 0) {
+		if (xhci_start(xhci)) {
+			xhci_halt(xhci);
+			return -ENODEV;
+		}
+		xhci->cmd_ring_state = CMD_RING_STATE_RUNNING;
+	}
+
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"Finished xhci_run for USB2 roothub");