• Maciej W. Rozycki's avatar
    defxx: Add missing DMA synchronisation calls · 8848761f
    Maciej W. Rozycki authored
    This adds DMA synchronisation calls needed in the receive path:
    
    1. To retrieve the Receive Status word that is prepended by the PDQ DMA
       engine in the receive buffer, and provides information about the
       frame received, including its size and any errors.
    
    2. To make data received available for copying in the small-frame case
       (size <= SKBUFF_RX_COPYBREAK) where the original DMA buffer will be
       returned to the receive descriptor ring and therefore its mapping
       retained.
    
       With DMA mapping error handling in place, added by the other patch,
       this may now also trigger where an attempt to map a newly allocated
       buffer for DMA has failed.  In that case data from the original buffer
       will be copied out and the buffer returned to the DMA descriptor ring.
    
    These calls may do nothing when data is in the host DMA addressing range
    of the FDDI interface, such as always on 32-bit systems, however their
    absence makes frame reception stop functioning reliably on systems that
    have memory beyond the low 4GB of the address space.
    Reported-by: default avatarRobert Coerver <Robert.Coerver@ll.mit.edu>
    Tested-by: default avatarRobert Coerver <Robert.Coerver@ll.mit.edu>
    Signed-off-by: default avatarMaciej W. Rozycki <macro@linux-mips.org>
    Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
    8848761f
defxx.c 114 KB