NetBSD master CVS tree commits

[The Source of All Evil <source>]

chuck
Tue Jul 16 18:11:19 EDT 1996
Update of /a/cvsroot/src/sys/dev/ic
In directory pain.lcs.mit.edu:/a/tmp/cvs-serv1568

Modified Files:
        midwayreg.h midwayvar.h midway.c 
Log Message:
midway fixes + new stuff:
 - merged multiple DRQ/DTQ ADD macros into a single DRQ and a single DTQ 
   macro with a uniform interface to make the code simpler and easier to read.

 - en_start: only update atm_flags if EN_MBUF_OPT is enabled (which it 
        should be)

 - for alburst: make sure we don't DMA more bytes than we need (on both 
        tx and rx).   if the alburst is larger than we need, drop to
        MIDDMA_WORD mode.

 - major change: enable the use of byte and 2 byte DMA on the trasmit side.
   this allows us to DMA from non-word sized/aligned mbufs directly.    
   [the old code would always call en_mfix which would copy (or move) the 
    data in order to ensure proper alignment...   it turns out TCP gives
    us non-word sized/aligned mbufs when it is retransmitting, so we needed
    to handle this case more efficiently.]    the following functions
   were changed to make this work:
    - en_dqneed: add an arg to let us know if we are transmitting or not.
        if we are TX, then we must take into account byte DMAs when 
        estimating the number of DTQs we will need for a buffer
    - en_start: only mfix mbufs if DMA is disabled
    - en_txdma: only set launch.nodma if we have en_mfix'd the mbuf chain
        also, we may need a DTQ to flush the chip's internal byte buffer
    - en_txlaunch: only attempt a copy if we have the proper alignment.
        add byte dma code for the front and end of the buffer.
        make sure the internal dma buffer is flushed out.
    - stats: keep track of how many times we have to use byte sized DMA

midwayreg:
 - add byte/2byte DMA defines

midwayvar: 
 - add new stat counter to monitor less-than-word lengthed DMA