Re: [RFC PATCH 31/40] soundwire: intel: move shutdown() callback and don't export symbol

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+void intel_shutdown(struct snd_pcm_substream *substream,
+            struct snd_soc_dai *dai)
+{
+    struct sdw_cdns_dma_data *dma;
+
+    dma = snd_soc_dai_get_dma_data(dai, substream);
+    if (!dma)
+        return;
+
+    snd_soc_dai_set_dma_data(dai, substream, NULL);
+    kfree(dma);
+}

Correct me if I'm wrong, but do we really need to _get_dma_ here?
_set_dma_ seems bulletproof, same for kfree.

I must admit I have no idea why we have a reference to DMAs here, this looks
like an abuse to store a dai-specific context, and the initial test looks
like copy-paste to detect invalid configs, as done in other callbacks. Vinod
and Sanyog might have more history than me here.

I dont see snd_soc_dai_set_dma_data() call for
sdw_cdns_dma_data so somthing is missing (at least in upstream code)

IIRC we should have a snd_soc_dai_set_dma_data() in alloc or some
initialization routine and we free it here.. Sanyog?

Vinod, I double-checked that we do not indeed have a call to snd_soc_dai_dma_data(), but there is code in cdns_set_stream() that sets the relevant dai->playback/capture_dma_data, see below

I am not a big fan of this code, touching the ASoC core internal fields isn't a good idea in general.

Also not sure why for a DAI we need both _drvdata and _dma_data (especially for this case where the information stored has absolutely nothing to do with DMAs).

If the idea was to keep a context that is direction-dependent, that's likely unnecessary. For the Intel/Cadence case the interfaces can be configured as playback OR capture, not both concurrently, so the "dma" information could have been stored in the generic DAI _drvdata.

I have other things to look into for now but this code will likely need to be cleaned-up at some point to remove unnecessary parts.

int cdns_set_sdw_stream(struct snd_soc_dai *dai,
			void *stream, bool pcm, int direction)
{
	struct sdw_cdns *cdns = snd_soc_dai_get_drvdata(dai);
	struct sdw_cdns_dma_data *dma;

	dma = kzalloc(sizeof(*dma), GFP_KERNEL);
	if (!dma)
		return -ENOMEM;

	if (pcm)
		dma->stream_type = SDW_STREAM_PCM;
	else
		dma->stream_type = SDW_STREAM_PDM;

	dma->bus = &cdns->bus;
	dma->link_id = cdns->instance;

	dma->stream = stream;

>>> this is equivalent to snd_soc_dai_dma_data()

	if (direction == SNDRV_PCM_STREAM_PLAYBACK)
		dai->playback_dma_data = dma;
	else
		dai->capture_dma_data = dma;
<<<<
	return 0;
}
EXPORT_SYMBOL(cdns_set_sdw_stream);
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