linux-kernel - Re: [PATCH 2/3] ALSA: compress: document the compress gapless audio state machine

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Message-ID: <248f7bef-c3d4-2d2e-ffa4-0d372879c8ae@linux.intel.com>
Date:   Mon, 22 Jun 2020 08:22:00 -0500
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     Vinod Koul <vkoul@...nel.org>
Cc:     linux-kernel@...r.kernel.org, alsa-devel@...a-project.org,
        Charles Keepax <ckeepax@...nsource.cirrus.com>,
        Takashi Iwai <tiwai@...e.com>
Subject: Re: [PATCH 2/3] ALSA: compress: document the compress gapless audio
 state machine



On 6/22/20 12:34 AM, Vinod Koul wrote:
> On 19-06-20, 09:27, Pierre-Louis Bossart wrote:
>>
>>> +For Gapless, we move from running state to partial drain and back, along
>>> +with setting of meta_data and signalling for next track ::
>>> +
>>> +
>>> +                                        +----------+
>>> +                compr_drain_notify()    |          |
>>> +              +------------------------>|  RUNNING |
>>> +              |                         |          |
>>> +              |                         +----------+
>>> +              |                              |
>>> +              |                              |
>>> +              |                              | compr_next_track()
>>> +              |                              |
>>> +              |                              V
>>> +              |                         +----------+
>>> +              |                         |          |
>>> +              |                         |NEXT_TRACK|
>>> +              |                         |          |
>>> +              |                         +----------+
>>> +              |                              |
>>> +              |                              |
>>> +              |                              | compr_partial_drain()
>>> +              |                              |
>>> +              |                              V
>>> +              |                         +----------+
>>> +              |                         |          |
>>> +              +------------------------ | PARTIAL_ |
>>> +                                        |  DRAIN   |
>>> +                                        +----------+
>>
>> May I suggest having a single state machine, not a big one and an additional
>> partial one. It would help explain why in one case compr_drain_notify()
>> triggers a transition to RUNNING while in the other one it goes to SETUP.
>>
>> I realize it's more complicated to edit but it'd be easier on
>> reviewers/users.
> 
> Ell adding stop and transitions would really make it complicated and
> gapless is a bit different handling and it looks cleaner this way IMO,
> so lets stick to this. Feel free to create one if you are up for it.

if you don't want to change the visuals then please add a paragraph 
explaining the different uses of compr_drain_notify().