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 9708dbb52b702b49b00b11ca45991088d370f9fe..78b65f70812f1f82ccc7d60404bdf044a167bb98 100644 (file)
--- a/drivers/usb/host/xhci-hub.c
+++ b/drivers/usb/host/xhci-hub.c
@@ -1297,6 +1297,17 @@ 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 ebf09503be3946f250c7192039c3474b90405cfc..ceb0a02c4ac37b6a90c89d8842a60cfb86c16154 100644 (file)
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -144,9 +144,11 @@ static 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 2b8df83dad38d97aed2887829d837ecdba1b36b4..9f76ad09911b4f3915ae6a45748a6d836d51fdc2 100644 (file)
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1607,7 +1607,7 @@ 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!"