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  1. May 24, 2021
    • Stephan Gerhold's avatar
      ASoC: codecs: Add driver for NXP/Goodix TFA989x (TFA1) amplifiers · af00978a
      Stephan Gerhold authored
      NXP's TFA98xx (now part of Goodix) are fairly popular speaker amplifiers
      used in many smartphones and tablets. Most of them are sold as "smart
      amplifiers" with built-in "CoolFlux DSP" that is used for volume control,
      plus a "sophisticated speaker-boost and protection algorithm".
      
      Unfortunately, they are also almost entirely undocumented. The short
      datasheets (e.g. [1] for TFA9897) describe the available features,
      but do not provide any information about the registers or how to use
      the "CoolFlux DSP".
      
      The amplifiers are most often configured through proprietary userspace
      libraries. There are also some (rather complex) kernel drivers (e.g. [2])
      but even those rely on obscure firmware blobs for configuration (so-called
      "containers"). They seem to contain different "profiles" with tuned speaker
      settings, sample rates and volume steps (which would be better exposed
      as separate ALSA mixers).
      
      The format of the firmware files seems to have changed a lot over the time,
      so it's not even possible to simply re-use the firmware originally provided
      by the vendor.
      
      Overall, it seems close to impossible to develop a proper mainline driver
      for these amplifiers that could make proper use of the built-in DSP.
      
      This commit implements a compromise: At least the TFA1 family of the
      TFA98xx amplifiers (usually called TFA989x) provide a way to *bypass*
      the DSP using a special register sequence. The register sequence can be
      found in similar variations in the kernel drivers from lots of vendors
      e.g. in [3] and was probably mainly used for factory testing.
      
      With the DSP bypassed, the amplifier acts mostly like a dumb standard
      speaker amplifier, without (hardware) volume control. However, the setup
      is much simpler and it works without any obscure firmware.
      
      This driver implements the DSP bypass combined with chip-specific
      initialization sequences adapted from [2]. Only TFA9895 is supported in
      this initial commit. Except for the lack of volume control I can not hear
      any difference with or without the DSP, it works just fine.
      
      This driver allows the speaker to work on mainline Linux running on the
      Samsung Galaxy A3/A5 (2015) [TFA9895] and Alcatel Idol 3 [TFA9897].
      TFA9897 support will be added in separate patch set later.
      
      [1]: https://product.goodix.com/en/docview/TFA9897%20SDS_Rev.3.1?objectId=47&objectType=document&version=78
      [2]: https://source.codeaurora.org/external/mas/tfa98xx
      [3]: https://github.com/sonyxperiadev/kernel/blob/57b5050e340f40a88e1ddb8d16fd9adb44418923/sound/soc/codecs/tfa98xx.c#L1422-L1462
      
      
      
      Signed-off-by: default avatarStephan Gerhold <stephan@gerhold.net>
      Link: https://lore.kernel.org/r/20210513104129.36583-2-stephan@gerhold.net
      
      
      Signed-off-by: default avatarMark Brown <broonie@kernel.org>
      af00978a
  2. May 21, 2021
  3. May 20, 2021
  4. May 19, 2021
  5. May 18, 2021
  6. May 14, 2021
  7. May 12, 2021
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