• Alan Stern's avatar
    USB: EHCI: update toggle state for linked QHs · b18ffd49
    Alan Stern authored
    This patch (as1245) fixes a bug in ehci-hcd.  When an URB is queued
    for an endpoint whose QH is already in the LINKED state, the QH
    doesn't get refreshed.  As a result, if usb_clear_halt() was called
    during the time that the QH was linked but idle, the data toggle value
    in the QH doesn't get reset.
    
    The symptom is that after a clear_halt, data gets lost and transfers
    time out.  This problem is starting to show up now because the
    "ehci-hcd unlink speedups" patch causes QHs with no queued URBs to
    remain linked for a suitable time.
    
    The patch utilizes the new endpoint_reset mechanism to fix the
    problem.  When an endpoint is reset, the new method forcibly unlinks
    the QH (if necessary) and safely updates the toggle value.  This
    allows qh_update() to be simplified and avoids using usb_device's
    toggle bits in a rather unintuitive way.
    Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    CC: David Brownell <david-b@pacbell.net>
    Tested-by: default avatarDavid <david@unsolicited.net>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    b18ffd49
ehci-q.c 32.7 KB