• Sarah Sharp's avatar
    USB: Support for allocating USB 3.0 streams. · eab1cafc
    Sarah Sharp authored
    Bulk endpoint streams were added in the USB 3.0 specification.  Streams
    allow a device driver to overload a bulk endpoint so that multiple
    transfers can be queued at once.
    
    The device then decides which transfer it wants to work on first, and can
    queue part of a transfer before it switches to a new stream.  All this
    switching is invisible to the device driver, which just gets a completion
    for the URB.  Drivers that use streams must be able to handle URBs
    completing in a different order than they were submitted to the endpoint.
    
    This requires adding new API to set up xHCI data structures to support
    multiple queues ("stream rings") per endpoint.  Drivers will allocate a
    number of stream IDs before enqueueing URBs to the bulk endpoints of the
    device, and free the stream IDs in their disconnect function.  See
    Documentation/usb/bulk-streams.txt for details.
    
    The new mass storage device class, USB Attached SCSI Protocol (UASP), uses
    these streams API.
    Signed-off-by: default avatarSarah Sharp <sarah.a.sharp@linux.intel.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
    eab1cafc
bulk-streams.txt 3.16 KB