linux/Documentation/sound/oss/ESS
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   1Documentation for the ESS AudioDrive chips
   2
   3In 2.4 kernels the SoundBlaster driver not only tries to detect an ESS chip, it
   4tries to detect the type of ESS chip too. The correct detection of the chip 
   5doesn't always succeed however, so unless you use the kernel isapnp facilities
   6(and you chip is pnp capable) the default behaviour is 2.0 behaviour which
   7means: only detect ES688 and ES1688.
   8
   9All ESS chips now have a recording level setting. This is a need-to-have for
  10people who want to use their ESS for recording sound.
  11
  12Every chip that's detected as a later-than-es1688 chip has a 6 bits logarithmic
  13master volume control.
  14
  15Every chip that's detected as a ES1887 now has Full Duplex support. Made a 
  16little testprogram that shows that is works, haven't seen a real program that
  17needs this however.
  18
  19For ESS chips an additional parameter "esstype" can be specified. This controls
  20the (auto) detection of the ESS chips. It can have 3 kinds of values:
  21
  22-1   Act like 2.0 kernels: only detect ES688 or ES1688.
  230        Try to auto-detect the chip (may fail for ES1688)
  24688  The chip will be treated as  ES688
  251688  ,,  ,,   ,,  ,,    ,,   ,, ES1688
  261868  ,,  ,,   ,,  ,,    ,,   ,, ES1868
  271869  ,,  ,,   ,,  ,,    ,,   ,, ES1869
  281788  ,,  ,,   ,,  ,,    ,,   ,, ES1788
  291887  ,,  ,,   ,,  ,,    ,,   ,, ES1887
  301888  ,,  ,,   ,,  ,,    ,,   ,, ES1888
  31
  32Because Full Duplex is supported for ES1887 you can specify a second DMA
  33channel by specifying module parameter dma16. It can be one of: 0, 1, 3 or 5.
  34
  35