• Mathias Nyman's avatar
    xhci: Ensure a command structure points to the correct trb on the command ring · ec7e43e2
    Mathias Nyman authored
    If a command on the command ring needs to be cancelled before it is handled
    it can be turned to a no-op operation when the ring is stopped.
    We want to store the command ring enqueue pointer in the command structure
    when the command in enqueued for the cancellation case.
    
    Some commands used to store the command ring dequeue pointers instead of enqueue
    (these often worked because enqueue happends to equal dequeue quite often)
    
    Other commands correctly used the enqueue pointer but did not check if it pointed
    to a valid trb or a link trb, this caused for example stop endpoint command to timeout in
    xhci_stop_device() in about 2% of suspend/resume cases.
    
    This should also solve some weird behavior happening in command cancellation cases.
    
    This patch is based on a patch submitted by Sarah Sharp to linux-usb, but
    then forgotten:
        http://marc.info/?l=linux-usb&m=136269803207465&w=2
    
    This patch should be backported to kernels as old as 3.7, that contain
    the commit b92cc66c "xHCI: add aborting
    command ring function"
    Signed-off-by: default avatarMathias Nyman <mathias.nyman@linux.intel.com>
    Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
    Cc: stable@vger.kernel.org
    ec7e43e2
xhci-ring.c 124 KB