• Giuseppe CAVALLARO's avatar
    stmmac: add CHAINED descriptor mode support (V4) · 286a8372
    Giuseppe CAVALLARO authored
    This patch enhances the STMMAC driver to support CHAINED mode of
    descriptor.
    
    STMMAC supports DMA descriptor to operate both in dual buffer(RING)
    and linked-list(CHAINED) mode. In RING mode (default) each descriptor
    points to two data buffer pointers whereas in CHAINED mode they point
    to only one data buffer pointer.
    
    In CHAINED mode each descriptor will have pointer to next descriptor in
    the list, hence creating the explicit chaining in the descriptor itself,
    whereas such explicit chaining is not possible in RING mode.
    
    First version of this work has been done by Rayagond.
    Then the patch has been reworked avoiding ifdef inside the C code.
    A new header file has been added to define all the functions needed for
    managing enhanced and normal descriptors.
    In fact, these have to be specialized according to the ring/chain usage.
    Two new C files have been also added to implement the helper routines
    needed to manage: jumbo frames, chain and ring setup (i.e. desc3).
    Signed-off-by: default avatarRayagond Kokatanur <rayagond@vayavyalabs.com>
    Signed-off-by: default avatarGiuseppe Cavallaro <peppe.cavallaro@st.com>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    286a8372
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