1. 23 4月, 2009 1 次提交
    • D
      palm_bk3710: UDMA performance fix · db2f38c2
      David Brownell 提交于
      Fix UDMA throughput bug:  tCYC averages t2CYCTYP/2, but the code
      previously assumed it was the same as t2CYCTYP.  (That is, it was
      using just one clock edge, not both.)  Move the table's type
      declaration so it's adjacent to the table, making it more clear
      what those numbers mean.
      
      On one system this change increased throughput by almost 4x: UDMA/66
      sometimes topped 23 MB/sec (on a drive known to do much better).  On
      another system it was around a 10% win (UDMA/66 up to 7+ MB/sec).
      
      The difference might be caused by the ratio between memory and IDE
      clocks.  In the system with large speedup, this was exactly 2 (as a
      workaround for a rev 1.1 silicon bug).  The other system used a more
      standard ratio of 1.63 (and rev 2.1 silicon) ... clock domain synch
      might have some issues, they're not unheard-of.
      Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
      Acked-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
      Signed-off-by: NBartlomiej Zolnierkiewicz <bzolnier@gmail.com>
      db2f38c2
  2. 18 4月, 2009 39 次提交