stmmac: add CHAINED descriptor mode support (V4)
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:Rayagond Kokatanur <rayagond@vayavyalabs.com> Signed-off-by:
Giuseppe Cavallaro <peppe.cavallaro@st.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
parent
38fe7a93
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