linux-kernel - Re: [alsa-devel] [PATCH] ASoC: da7219: check SRM lock in trigger callback

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Date:   Tue, 11 Feb 2020 15:49:06 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     "Sridharan, Ranjani" <ranjani.sridharan@...el.com>
Cc:     "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        Support Opensource <Support.Opensource@...semi.com>,
        Takashi Iwai <tiwai@...e.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Chiang, Mac" <mac.chiang@...el.com>,
        Mark Brown <broonie@...nel.org>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        "Lu, Brent" <brent.lu@...el.com>,
        "cychiang@...gle.com" <cychiang@...gle.com>
Subject: Re: [alsa-devel] [PATCH] ASoC: da7219: check SRM lock in trigger
 callback



>>> Are you talking about the change in this commit acbf27746ecfa96b
>>> "ASoC: pcm: update FE/BE trigger order based on the command"?
>>>
>>> We made this change to handle xruns during pause/release particularly on
>>> the Intel HDA platforms.
>>
>> this change was just to mirror the behavior between start/stop, I
>> thought there was a patch where we moved to TRIGGER_POST by default?
>>
>> What I am trying to figure out if whether using TRIGGER_PRE is ok or not
>> for the SOF firmware.
>>
> 
> Ahh yes, it was part of the same series as this one. fd274c2b7267b  "ASoC:
> SOF: topology: set trigger order for FE DAI link"
> 
> TRIGGER_PRE won't really work in the case of SOF. We need the BE DAI to be
> triggered before the FE DAI during start to prevent the xruns during
> pause/release.

Thanks Ranjani. That information closes the door on the idea of playing 
with the trigger order suggested earlier in the thread, so my guess is 
that we really need to expose the MCLK/BCLK with the clk API and turn 
them on/off from the machine driver as needed. I hope is that we don't 
need the FSYNC as well, that would be rather painful to implement.