[alsa-devel] [PATCH v4 07/13] soundwire: Add stream configuration APIs

[Pierre-Louis Bossart]

> +static int _sdw_prepare_stream(struct sdw_stream_runtime *stream)
> +{
> +	struct sdw_master_runtime *m_rt = stream->m_rt;
> +	struct sdw_bus *bus = m_rt->bus;
> +	struct sdw_master_prop *prop = NULL;
> +	struct sdw_bus_params params;
> +	int ret;
> +
> +	prop = &bus->prop;
> +	memcpy(&params, &bus->params, sizeof(params));
> +
> +	/* TODO: Support Asynchronous mode */
> +	if ((prop->max_freq % stream->params.rate) != 0) {
> +		dev_err(bus->dev, "Async mode not supported");
> +		return -EINVAL;
> +	}
> +
> +	/* Increment cumulative bus bandwidth */
> +	bus->params.bandwidth += m_rt->stream->params.rate *
> +		m_rt->ch_count * m_rt->stream->params.bps;

This also does not work for device-to-device communication, see e.g.
the earlier documentation.

ch_count: Number of channels handled by the Master for
+ * this stream, can be zero.

should it be m_rt->stream->params->ch_count?


> +static int _sdw_deprepare_stream(struct sdw_stream_runtime *stream)
> +{
> +	struct sdw_master_runtime *m_rt = stream->m_rt;
> +	struct sdw_bus *bus = m_rt->bus;
> +	int ret = 0;
> +
> +	/* De-prepare port(s) */
> +	ret = sdw_prep_deprep_ports(m_rt, false);
> +	if (ret < 0) {
> +		dev_err(bus->dev, "De-prepare port(s) failed: %d", ret);
> +		return ret;
> +	}
> +
> +	bus->params.bandwidth -= m_rt->stream->params.rate *
> +		m_rt->ch_count * m_rt->stream->params.bps;

And same here, the ch_count can be zero.

> +
> +	if (!bus->params.bandwidth) {
> +		bus->params.row = 0;
> +		bus->params.col = 0;
> +		goto exit;

What is the intent with this test+goto? Shouldn't you program the 
parameters if you want to change the frame shape?

> +	}
> +
> +	/* Program params */
> +	ret = sdw_program_params(bus);
> +	if (ret < 0) {
> +		dev_err(bus->dev, "Program params failed: %d", ret);
> +		return ret;
> +	}
> +
> +	return do_bank_switch(stream);
> +
> +exit:
> +	stream->state = SDW_STREAM_DEPREPARED;
> +
> +	return ret;
> +}