• Alan Stern's avatar
    UHCI: Eliminate asynchronous skeleton Queue Headers · 17230acd
    Alan Stern authored
    This patch (as856) attempts to improve the performance of uhci-hcd by
    removing the asynchronous skeleton Queue Headers.  They don't contain
    any useful information but the controller has to read through them at
    least once every millisecond, incurring a non-zero DMA overhead.
    
    Now all the asynchronous queues are combined, along with the period-1
    interrupt queue, into a single list with a single skeleton QH.  The
    start of the low-speed control, full-speed control, and bulk sublists
    is determined by linear search.  Since there should rarely be more
    than a couple of QHs in the list, the searches should incur a much
    smaller total load than keeping the skeleton QHs.
    Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    17230acd
uhci-hcd.c 25.7 KB