linux-kernel - Re: [PATCH 4/6] soundwire: stream: do not update parameters during DISABLED-PREPARED transition

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Date:   Fri, 10 Jan 2020 12:25:15 +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>,
        Sanyog Kale <sanyog.r.kale@...el.com>
Subject: Re: [PATCH 4/6] soundwire: stream: do not update parameters during
 DISABLED-PREPARED transition

On 08-01-20, 11:54, Pierre-Louis Bossart wrote:
> After a system suspend, the ALSA/ASoC core will invoke the .prepare()
> callback and a TRIGGER_START when INFO_RESUME is not supported.
> 
> Likewise, when an underflow occurs, the .prepare callback will be invoked.
> 
> In both cases, the stream can be in DISABLED mode, and will transition
> into the PREPARED mode. We however don't want the bus bandwidth to be
> recomputed.
> 
> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@...ux.intel.com>
> ---
>  drivers/soundwire/stream.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/soundwire/stream.c b/drivers/soundwire/stream.c
> index bd0bddf73830..c28ce7f0d742 100644
> --- a/drivers/soundwire/stream.c
> +++ b/drivers/soundwire/stream.c
> @@ -1460,7 +1460,8 @@ static void sdw_release_bus_lock(struct sdw_stream_runtime *stream)
>  	}
>  }
>  
> -static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
> +static int _sdw_prepare_stream(struct sdw_stream_runtime *stream,
> +			       bool update_params)
>  {
>  	struct sdw_master_runtime *m_rt;
>  	struct sdw_bus *bus = NULL;
> @@ -1480,6 +1481,9 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
>  			return -EINVAL;
>  		}
>  
> +		if (!update_params)
> +			goto program_params;
> +
>  		/* Increment cumulative bus bandwidth */
>  		/* TODO: Update this during Device-Device support */
>  		bus->params.bandwidth += m_rt->stream->params.rate *
> @@ -1495,6 +1499,7 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
>  			}
>  		}
>  
> +program_params:
>  		/* Program params */
>  		ret = sdw_program_params(bus);
>  		if (ret < 0) {
> @@ -1544,6 +1549,7 @@ static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
>   */
>  int sdw_prepare_stream(struct sdw_stream_runtime *stream)
>  {
> +	bool update_params = true;
>  	int ret;
>  
>  	if (!stream) {
> @@ -1567,7 +1573,16 @@ int sdw_prepare_stream(struct sdw_stream_runtime *stream)
>  		goto state_err;
>  	}
>  
> -	ret = _sdw_prepare_stream(stream);
> +	/*
> +	 * when the stream is DISABLED, this means sdw_prepare_stream()
> +	 * is called as a result of an underflow or a resume operation.
> +	 * In this case, the bus parameters shall not be recomputed, but
> +	 * still need to be re-applied
> +	 */
> +	if (stream->state == SDW_STREAM_DISABLED)
> +		update_params = false;

Should this not be handled by the caller..? I do not like to deduce this
here as the info is already available in dai driver, so go ahead and
propagate it and get it from caller when it is required..

-- 
~Vinod