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Date:      Mon, 23 Aug 1999 20:19:46 -0700 (PDT)
From:      Bill Paul <wpaul@FreeBSD.org>
To:        cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org
Subject:   cvs commit: src/sys/pci if_pn.c if_pnreg.h
Message-ID:  <199908240319.UAA35417@freefall.freebsd.org>

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wpaul       1999/08/23 20:19:46 PDT

  Modified files:
    sys/pci              if_pn.c if_pnreg.h 
  Log:
  Change PN_RXLEN from 1518 bytes to 1536 bytes. The chip always DMAs data
  in 4 byte chunks. It turns out that with the 82c169C on the Netgear
  FA-310TX Rev D2, if you tell the chip you have reserved a buffer of 1518
  bytes, it will actually treat it as 1516 bytes since 1518 is divisible
  by four. Consequently, a packet of 1514 bytes will always end up consuming
  two buffers: the last coupleof bytes will spill over into the next
  descriptor. This causes the pn_rx_bug_war() routine to trip unnecessarily.
  
  I'm not sure if the 82c169B or 82c168 chips behave the same way; I'll
  have to check them. In any case, this change should work just as well
  with them. Note that the FA-310TX Rev D2 also has a Broadcom PHY
  instead of a Level One LXT970 PHY, however this shouldn't make any
  difference as far as the driver is concerned.
  
  This change also allows me to do a way with one rounding overation in
  pn_rx-buf_war().
  
  Revision  Changes    Path
  1.25      +4 -4      src/sys/pci/if_pn.c
  1.16      +2 -2      src/sys/pci/if_pnreg.h



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