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    SubjectRe: [PATCH 10/11] ASoC: qdsp6-dai: add gapless support
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    >> right, but the key point is 'switch between streams'. That means a
    >> more complex/capable implementation that should be advertised as such
    >> to applications. This is not the default behavior assumed initially:
    >> to allow for minimal implementations in memory-constrained devices, we
    >> assumed gapless was supported with a single decoder.
    >>
    >> Maybe the right way to do this is extend the snd_compr_caps structure:
    >>
    >> /**
    >>   * struct snd_compr_caps - caps descriptor
    >>   * @codecs: pointer to array of codecs
    >>   * @direction: direction supported. Of type snd_compr_direction
    >>   * @min_fragment_size: minimum fragment supported by DSP
    >>   * @max_fragment_size: maximum fragment supported by DSP
    >>   * @min_fragments: min fragments supported by DSP
    >>   * @max_fragments: max fragments supported by DSP
    >>   * @num_codecs: number of codecs supported
    >>   * @reserved: reserved field
    >>   */
    >> struct snd_compr_caps {
    >>      __u32 num_codecs;
    >>      __u32 direction;
    >>      __u32 min_fragment_size;
    >>      __u32 max_fragment_size;
    >>      __u32 min_fragments;
    >>      __u32 max_fragments;
    >>      __u32 codecs[MAX_NUM_CODECS];
    >>      __u32 reserved[11];
    >> } __attribute__((packed, aligned(4)));
    >>
    >>
    >> and use a reserved field to provide info on capabilities, and filter
    >> the set_codec_params() addition based this capability - i.e. return
    >> -ENOTSUP in 'traditional' implementations based on a single
    >> 'stream'/decoder instance.

    I think this is also what Mark was referring to earlier.

    > Sounds good!
    > I will give it a go and see how it ends up!

    Glad to see this discussion progressing.

    We may also want to document the 3 possible ways of supporting gapless
    playback while we are at it:
    a) with the existing single decoder assumption
    b) with your suggested solution with a switch at the DSP level
    c) with 2 streams at the userspace level and a switch/x-fade at the DSP
    level - which may simplify userspace quite a bit and was the initial
    design in a non-Linux OS.

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