Re: [PATCH 08/19] ASoC: amd: ps: add soundwire dma driver dma ops

[Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>]

>>> +	sdw_data->sdw_stream[stream_id] = substream;
>>> +	size = params_buffer_bytes(params);
>>> +	period_bytes = params_period_bytes(params);
>>> +	sdw_stream_data->dma_addr = substream->runtime->dma_addr;
>>> +	sdw_stream_data->num_pages = (PAGE_ALIGN(size) >> PAGE_SHIFT);
>>> +	acp63_config_dma(sdw_stream_data, stream_id);
>>> +	ret = acp63_configure_sdw_ringbuffer(sdw_stream_data->acp_base, stream_id, size);
>>> +	if (ret) {
>>> +		dev_err(component->dev, "Invalid channel type\n");
>>> +		return -EINVAL;
>>> +	}
>>> +	switch (stream_id) {
>>> +	case ACP_SDW_AUDIO_TX:
>>> +		water_mark_size_reg = ACP_AUDIO_TX_INTR_WATERMARK_SIZE;
>>> +		irq_mask = BIT(ACP_AUDIO_TX_THRESHOLD);
>>> +		acp_ext_intr_cntl_reg = ACP_EXTERNAL_INTR_CNTL;
>>> +		break;
>> so there's ONE resource to deal with external codecs? How does this work
>> if you have a headset codec and an amplifier?
> Are you referring to playing a same stream over headset codec and
> amplifier?
> It's all about channel selection from DMA perspective.
> We have tested speaker aggregation and headset playback use cases.

No, I wasn't asking about playing the same content to different sinks.

I was referring to playing/recording different content to/from different
devices.

Even when interfacing with a single device, there are interesting
topologies in the SDCA spec that would require multiple DMA transfers
conveying unrelated content (or processed content from the same source).