linux-kernel - Re: [PATCH] soundwire: stream: only change state if needed

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Date:   Fri, 20 Mar 2020 19:45:28 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
Cc:     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,
        slawomir.blauciak@...el.com,
        Bard liao <yung-chuan.liao@...ux.intel.com>,
        Rander Wang <rander.wang@...ux.intel.com>,
        Ranjani Sridharan <ranjani.sridharan@...ux.intel.com>,
        Hui Wang <hui.wang@...onical.com>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [PATCH] soundwire: stream: only change state if needed

On 17-03-20, 05:51, Pierre-Louis Bossart wrote:
> In a multi-cpu DAI context, the stream routines may be called from
> multiple DAI callbacks. Make sure the stream state only changes for
> the first call, and don't return error messages if the target state is
> already reached.

For stream-apis we have documented explicitly in Documentation/driver-api/soundwire/stream.rst

"Bus implements below API for allocate a stream which needs to be called once
per stream. From ASoC DPCM framework, this stream state maybe linked to
.startup() operation.

.. code-block:: c

  int sdw_alloc_stream(char * stream_name); "

This is documented for all stream-apis.

This can be resolved by moving the calling of these APIs from
master-dais/slave-dais to machine-dais. They are unique in the card.

> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/stream.c | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)
> 
> diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
> index 1b43d03c79ea..3319121cd706 100644
> --- a/drivers/soundwire/stream.c
> +++ b/drivers/soundwire/stream.c
> @@ -1572,6 +1572,7 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream)
>  	sdw_acquire_bus_lock(stream);
>  
>  	if (stream->state == SDW_STREAM_PREPARED) {
> +		/* nothing to do */
>  		ret = 0;
>  		goto state_err;
>  	}
> @@ -1661,6 +1662,12 @@ int sdw_enable_stream(struct sdw_stream_runtime *stream)
>  
>  	sdw_acquire_bus_lock(stream);
>  
> +	if (stream->state == SDW_STREAM_ENABLED) {
> +		/* nothing to do */
> +		ret = 0;
> +		goto state_err;
> +	}
> +
>  	if (stream->state != SDW_STREAM_PREPARED &&
>  	    stream->state != SDW_STREAM_DISABLED) {
>  		pr_err("%s: %s: inconsistent state state %d\n",
> @@ -1744,6 +1751,12 @@ int sdw_disable_stream(struct sdw_stream_runtime *stream)
>  
>  	sdw_acquire_bus_lock(stream);
>  
> +	if (stream->state == SDW_STREAM_DISABLED) {
> +		/* nothing to do */
> +		ret = 0;
> +		goto state_err;
> +	}
> +
>  	if (stream->state != SDW_STREAM_ENABLED) {
>  		pr_err("%s: %s: inconsistent state state %d\n",
>  		       __func__, stream->name, stream->state);
> @@ -1809,6 +1822,12 @@ int sdw_deprepare_stream(struct sdw_stream_runtime *stream)
>  
>  	sdw_acquire_bus_lock(stream);
>  
> +	if (stream->state == SDW_STREAM_DEPREPARED) {
> +		/* nothing to do */
> +		ret = 0;
> +		goto state_err;
> +	}
> +
>  	if (stream->state != SDW_STREAM_PREPARED &&
>  	    stream->state != SDW_STREAM_DISABLED) {
>  		pr_err("%s: %s: inconsistent state state %d\n",
> -- 
> 2.20.1

-- 
~Vinod