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    xhci: Prevent U1/U2 link pm states if exit latency is too long · 7e540895
    Mathias Nyman authored
    
    
    commit 0472bf06c6fd33c1a18aaead4c8f91e5a03d8d7b upstream.
    
    Don't allow USB3 U1 or U2 if the latency to wake up from the U-state
    reaches the service interval for a periodic endpoint.
    
    This is according to xhci 1.1 specification section 4.23.5.2 extra note:
    
    "Software shall ensure that a device is prevented from entering a U-state
     where its worst case exit latency approaches the ESIT."
    
    Allowing too long exit latencies for periodic endpoint confuses xHC
    internal scheduling, and new devices may fail to enumerate with a
    "Not enough bandwidth for new device state" error from the host.
    
    Cc: <stable@vger.kernel.org>
    Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    7e540895