linux-kernel - Re: [PATCH 07/11] soundwire: intel: Only call sdw stream APIs for the first cpu

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Message-ID: <20200828074918.GN2639@vkoul-mobl>
Date:   Fri, 28 Aug 2020 13:19:18 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     Bard Liao <yung-chuan.liao@...ux.intel.com>,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        tiwai@...e.de, broonie@...nel.org, gregkh@...uxfoundation.org,
        jank@...ence.com, srinivas.kandagatla@...aro.org,
        rander.wang@...ux.intel.com, ranjani.sridharan@...ux.intel.com,
        hui.wang@...onical.com, sanyog.r.kale@...el.com,
        mengdong.lin@...el.com, bard.liao@...el.com
Subject: Re: [PATCH 07/11] soundwire: intel: Only call sdw stream APIs for
 the first cpu_dai

On 26-08-20, 09:35, Pierre-Louis Bossart wrote:
> 
> > > -	ret = sdw_prepare_stream(dma->stream);
> > > +	/*
> > > +	 * All cpu dais belong to a stream. To ensure sdw_prepare_stream
> > > +	 * is called once per stream, we should call it only when
> > > +	 * dai = first_cpu_dai.
> > > +	 */
> > > +	if (first_cpu_dai == dai)
> > > +		ret = sdw_prepare_stream(dma->stream);
> > 
> > Hmmm why not use the one place which is unique in the card to call this,
> > hint machine dais are only called once.
> 
> we are already calling directly sdw_startup_stream() and
> sdw_shutdown_stream() from the machine driver.
> 
> We could call sdw_stream_enable() in the dailink .trigger as well, since it
> only calls the stream API.

Correct :)

> However for both .prepare() and .hw_free() there are a set of dai-level
> configurations using static functions defined only in intel.c, and I don't
> think we can move the code to the machine driver, or split the
> prepare/hw_free in two (dailink and dai operations).

Cant they be exported and continue to call those apis

> I am not against your idea, I am not sure if it can be done.
> 
> Would you be ok to merge this as a first step and let us work on an
> optimization later (which would require ASoC/SoundWire synchronization)?

The problem is that we add one flag then another and it does become an
issue eventually, better to do the right thing now than later.

-- 
~Vinod