• Alan Stern's avatar
    USB: EHCI: warn on unexpectedly active QH · fc0855f2
    Alan Stern authored
    This patch adds a new warning message to ehci-hcd.  The warning is
    triggered whenever the driver finds that the hardware has set the
    Active bit in a QH at a time when the driver expects the QH to be
    completely idle.  Such bugs have been observed by users in the past,
    and since they can lead to serious problems (such as inability to
    unlink an URB that never completes), it would be good to know about
    them when they occur.
    
    This won't fix these bugs; that's a bigger job for a later patch.  But
    success isn't guaranteed, since this depends on aspects of the
    hardware which are not documented in the EHCI spec or for which the
    spec's recommendations are clearly unworkable.  It therefore seems
    worthwhile to check for these bugs proactively.
    Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Reported-by: default avatarMichael Reutman <mreutman@epiqsolutions.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    fc0855f2
ehci-q.c 41.4 KB