• Sheetal's avatar
    ASoC: tegra: Fix ADX byte map · 6dfe70be
    Sheetal authored
    Byte mask for channel-1 of stream-1 is not getting enabled and this
    causes failures during ADX use cases. This happens because the byte
    map value 0 matches the byte map array and put() callback returns
    without enabling the corresponding bits in the byte mask.
    
    ADX supports 4 output streams and each stream can have a maximum of
    16 channels. Each byte in the input frame is uniquely mapped to a
    byte in one of these 4 outputs. This mapping is done with the help of
    byte map array via user space control setting. The byte map array
    size in the driver is 16 and each array element is of size 4 bytes.
    This corresponds to 64 byte map values.
    
    Each byte in the byte map array can have any value between 0 to 255
    to enable the corresponding bits in the byte mask. The value 256 is
    used as a way to disable the byte map. However the byte map array
    element cannot store this value. The put() callback disables the byte
    mask for 256 value and byte map value is reset to 0 for this case.
    This causes problems during subsequent runs since put() callback,
    for value of 0, just returns without enabling the byte mask. In short,
    the problem is coming because 0 and 256 control values are stored as
    0 in the byte map array.
    
    Right now fix the put() callback by actually looking at the byte mask
    array state to identify if any change is needed and update the fields
    accordingly. The get() callback needs an update as well to return the
    correct control value that user has set before. Note that when user
    set 256, the value is stored as 0 and byte mask is disabled. So byte
    mask state is used to either return 256 or the value from byte map
    array.
    
    Given above, this looks bit complicated and all this happens because
    the byte map array is tightly packed and cannot actually store the 256
    value. Right now the priority is to fix the existing failure and a TODO
    item is put to improve this logic.
    
    Fixes: 3c97881b ("ASoC: tegra: Fix kcontrol put callback in ADX")
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarSheetal <sheetal@nvidia.com>
    Reviewed-by: default avatarMohan Kumar D <mkumard@nvidia.com>
    Reviewed-by: default avatarSameer Pujar <spujar@nvidia.com>
    Link: https://lore.kernel.org/r/1688015537-31682-3-git-send-email-spujar@nvidia.comSigned-off-by: default avatarMark Brown <broonie@kernel.org>
    6dfe70be
tegra210_adx.c 15.2 KB