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Linux Cross Reference
Linux/Documentation/sound/VIA-chipset

Version: ~ [ 2.4.0 ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 Running sound cards on VIA chipsets
  2 
  3 o       There are problems with VIA chipsets and sound cards that appear to
  4         lock the hardware solidly. Test programs under DOS have verified the
  5         problem exists on at least some (but apparently not all) VIA boards
  6 
  7 o       VIA have so far failed to bother to answer support mail on the subject
  8         so if you are a VIA engineer feeling aggrieved as you read this 
  9         document go chase your own people. If there is a workaround please
 10         let us know so we can implement it.
 11 
 12 
 13 Certain patterns of ISA DMA access used for most PC sound cards cause the
 14 VIA chipsets to lock up. From the collected reports this appears to cover a
 15 wide range of boards. Some also lock up with sound cards under Win* as well.
 16 
 17 Linux implements a workaround providing your chipset is PCI and you compiled
 18 with PCI Quirks enabled. If so you will see a message
 19         "Activating ISA DMA bug workarounds"
 20 
 21 during booting. If you have a VIA PCI chipset that hangs when you use the
 22 sound and is not generating this message even with PCI quirks enabled
 23 please report the information to the linux-kernel list (see REPORTING-BUGS).
 24 
 25 If you are one of the tiny number of unfortunates with a 486 ISA/VLB VIA
 26 chipset board you need to do the following to build a special kernel for
 27 your board
 28 
 29         edit linux/include/asm-i386/dma.h
 30 
 31 change
 32 
 33 #define isa_dma_bridge_buggy    (0)
 34 
 35 to
 36 
 37 #define isa_dma_bridge_buggy    (1)
 38 
 39 and rebuild a kernel without PCI quirk support.
 40 
 41 
 42 Other than this particular glitch the VIA [M]VP* chipsets appear to work
 43 perfectly with Linux.

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