usb: host: xhci: Avoid XHCI resume delay if SSUSB device is not present
authorWesley Cheng <quic_wcheng@quicinc.com>
Thu, 19 Oct 2023 10:29:24 +0000 (13:29 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Sat, 21 Oct 2023 10:38:54 +0000 (12:38 +0200)
commit6add6dd345cb754ce18ff992c7264cabf31e59f6
tree370a1b2ed2eaac5199c7270d983398a01c708ca0
parenta5f928db59519a15e82ecba4ae3e7cbf5a44715a
usb: host: xhci: Avoid XHCI resume delay if SSUSB device is not present

There is a 120ms delay implemented for allowing the XHCI host controller to
detect a U3 wakeup pulse.  The intention is to wait for the device to retry
the wakeup event if the USB3 PORTSC doesn't reflect the RESUME link status
by the time it is checked.  As per the USB3 specification:

  tU3WakeupRetryDelay ("Table 7-12. LTSSM State Transition Timeouts")

This would allow the XHCI resume sequence to determine if the root hub
needs to be also resumed.  However, in case there is no device connected,
or if there is only a HSUSB device connected, this delay would still affect
the overall resume timing.

Since this delay is solely for detecting U3 wake events (USB3 specific)
then ignore this delay for the disconnected case and the HSUSB connected
only case.

[skip helper function, rename usb3_connected variable -Mathias ]

Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Signed-off-by: Mathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20231019102924.2797346-20-mathias.nyman@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/host/xhci.c