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From: Søren Schmidt <sos@FreeBSD.org>
Date: Tue, 21 Oct 2003 12:20:37 -0700 (PDT)
To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org,
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X-FreeBSD-CVS-Branch: HEAD
Subject: cvs commit: src/sys/dev/ata ata-all.h ata-chipset.c ata-dma.c
 ata-lowlevel.c ata-pci.c
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sos         2003/10/21 12:20:37 PDT

  FreeBSD src repository

  Modified files:
    sys/dev/ata          ata-all.h ata-chipset.c ata-dma.c 
                         ata-lowlevel.c ata-pci.c 
  Log:
  Fix the DMA problem that most severely hit on the DS3112a SATA chip
  in connection with Marvell based SATA->PATA dongles.
  
  The problem was caused by a combination of things working
  together to make it hard to spot...
  
  The ATA driver has always started the ATA command, then build
  the SG list for DMA and then finally started the DMA engine.
  While this is according to specs, it poses a potential
  problem as some controllers apparently do not allow for unlimitted
  time between starting the ATA command and starting the DMA engine.
  
  At about the same time as ATAng was committed there were lots
  of other changes applied, some of which was locking in parts
  that causes the busdma load functions to take significantly
  longer to load the SG list.
  
  This pushed the time spent between starting the ATA command and
  starting the DMA engine over the hill for some controllers
  (especially the Silicon Image DS3112a) and caused what looked
  like lost interrupts.
  
  The solution is to get all the SG list work or rather all
  busdma related stuff done before we even try to start anything.
  
  This has the nice side effect of seperating busdma out the
  way it should be, so the working of the ATA machinery is not
  cluttered up with busdma droppings, making the code easier
  to read and understand.
  
  Revision  Changes    Path
  1.66      +4 -2      src/sys/dev/ata/ata-all.h
  1.41      +12 -21    src/sys/dev/ata/ata-chipset.c
  1.122     +20 -19    src/sys/dev/ata/ata-dma.c
  1.21      +20 -17    src/sys/dev/ata/ata-lowlevel.c
  1.70      +3 -7      src/sys/dev/ata/ata-pci.c