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>
Tue, 28 Nov 2023 17:19:45 +0000 (17:19 +0000)
commitf83810e0ecda73bdad2c94d2db60f58c0a158e7a
tree73d9cdca1244e2452d91da9a52357db8760d6fc0
parentb7b01c7804775cb3586fed3c71bc8c38fcc77000
usb: host: xhci: Avoid XHCI resume delay if SSUSB device is not present

[ Upstream commit 6add6dd345cb754ce18ff992c7264cabf31e59f6 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
drivers/usb/host/xhci.c