xhci: Add grace period after xHC start to prevent premature runtime suspend.

commit 33e321586e37b642ad10594b9ef25a613555cd08 upstream.

After xHC controller is started, either in probe or resume, it can take
a while before any of the connected usb devices are visible to the roothub
due to link training.

It's possible xhci driver loads, sees no acivity and suspends the host
before the USB device is visible.

In one testcase with a hotplugged xHC controller the host finally detected
the connected USB device and generated a wake 500ms after host initial
start.

If hosts didn't suspend the device duringe training it probablty wouldn't
take up to 500ms to detect it, but looking at specs reveal USB3 link
training has a couple long timeout values, such as 120ms
RxDetectQuietTimeout, and 360ms PollingLFPSTimeout.

So Add a 500ms grace period that keeps polling the roothub for 500ms after
start, preventing runtime suspend until USB devices are detected.

Cc: stable@vger.kernel.org
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20220825150840.132216-3-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/usb/host/xhci-hub.c b/drivers/usb/host/xhci-hub.c
index 1bb48e53449e6e941c5730321baba8e99f430c60..b5a18817c8071e69507ecbedddacb129199082b5 100644 (file)
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1464,6 +1464,17 @@ int xhci_hub_status_data(struct usb_hcd *hcd, char *buf)
 
        status = bus_state->resuming_ports;
 
+       /*
+        * SS devices are only visible to roothub after link training completes.
+        * Keep polling roothubs for a grace period after xHC start
+        */
+       if (xhci->run_graceperiod) {
+               if (time_before(jiffies, xhci->run_graceperiod))
+                       status = 1;
+               else
+                       xhci->run_graceperiod = 0;
+       }
+
        mask = PORT_CSC | PORT_PEC | PORT_OCC | PORT_PLC | PORT_WRC | PORT_CEC;
 
        /* For each port, did anything change?  If so, set that bit in buf. */

diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index a9e72fee87a77b3ac78d7e927b3405d30452ae19..7fef6d9ed04f8ffaa3cdde86b5874e6f2f47cef3 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -149,9 +149,11 @@ int xhci_start(struct xhci_hcd *xhci)
                xhci_err(xhci, "Host took too long to start, "
                                "waited %u microseconds.\n",
                                XHCI_MAX_HALT_USEC);
-       if (!ret)
+       if (!ret) {
                /* clear state flags. Including dying, halted or removing */
                xhci->xhc_state = 0;
+               xhci->run_graceperiod = jiffies + msecs_to_jiffies(500);
+       }
 
        return ret;
 }

diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 3e6cb257fde5a1ef14f62e89e72da84a161d3fde..029ffcb13d62e8f79ae6f9530a18c0cca1ac77a6 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1811,7 +1811,7 @@ struct xhci_hcd {
 
        /* Host controller watchdog timer structures */
        unsigned int            xhc_state;
-
+       unsigned long           run_graceperiod;
        u32                     command;
        struct s3_save          s3;
 /* Host controller is dying - not responding to commands. "I'm not dead yet!"