• Dan Williams's avatar
    dmaengine: add fence support · 0403e382
    Dan Williams authored
    Some engines optimize operation by reading ahead in the descriptor chain
    such that descriptor2 may start execution before descriptor1 completes.
    If descriptor2 depends on the result from descriptor1 then a fence is
    required (on descriptor2) to disable this optimization.  The async_tx
    api could implicitly identify dependencies via the 'depend_tx'
    parameter, but that would constrain cases where the dependency chain
    only specifies a completion order rather than a data dependency.  So,
    provide an ASYNC_TX_FENCE to explicitly identify data dependencies.
    Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
async_tx.h 6.77 KB