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

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Date:   Tue, 11 Feb 2020 15:12:01 -0600
From:   Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
To:     "Sridharan, Ranjani" <ranjani.sridharan@...el.com>
Cc:     "Lu, Brent" <brent.lu@...el.com>,
        Adam Thomson <Adam.Thomson.Opensource@...semi.com>,
        "alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
        Support Opensource <Support.Opensource@...semi.com>,
        Liam Girdwood <lgirdwood@...il.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Takashi Iwai <tiwai@...e.com>,
        "Chiang, Mac" <mac.chiang@...el.com>,
        Mark Brown <broonie@...nel.org>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        "cychiang@...gle.com" <cychiang@...gle.com>
Subject: Re: [alsa-devel] [PATCH] ASoC: da7219: check SRM lock in trigger
 callback



On 2/11/20 2:37 PM, Sridharan, Ranjani wrote:
> 
>      > I think the patch is for those systems which enable I2S clocks in
>     pcm_start instead
>      > of pcm_prepare. It has no effect on systems already be able to
>     turn on clocks in
>      > supply widgets or set_bias_level() function.
>      >
>      > If the trigger type in the DAI link is TRIGGER_PRE, then the
>     trigger function of FE port
>      > (component or CPU DAI) will be called before codec driver's
>     trigger function. In this
>      > case we will be able to turn on the clock in time. However, if
>     the trigger type is
>      > TRIGGER_POST, then the patch does not help because just like what
>     you said, codec
>      > driver's trigger function is called first.
> 
>     IIRC we recently did a change to deal with underflows. Ranjani, can you
>     remind us what the issue was?
> 
> Hi Pierre,
> 
> 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.

Thanks!
-Pierre