ASoC: bcm: cygnus: Use managed DMA buffer allocation

Instead of manually managing its DMA buffers using
dma_{alloc,free}_coherent() lets the sound core take care of this using
managed buffers.

On one hand this reduces the amount of boiler plate code, but the main
motivation for the change is to use the shared code where possible. This
makes it easier to argue about correctness and that the code does not
contain subtle bugs like data leakage or similar.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Link: https://lore.kernel.org/r/20210106133650.13509-2-lars@metafoo.deSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/bcm/cygnus-pcm.c

@@ -636,36 +636,6 @@ static int cygnus_pcm_close(struct snd_soc_component *component,
 	return 0;
 }
 
-static int cygnus_pcm_hw_params(struct snd_soc_component *component,
-				struct snd_pcm_substream *substream,
-				struct snd_pcm_hw_params *params)
-{
-	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
-	struct snd_pcm_runtime *runtime = substream->runtime;
-	struct cygnus_aio_port *aio;
-
-	aio = cygnus_dai_get_dma_data(substream);
-	dev_dbg(asoc_rtd_to_cpu(rtd, 0)->dev, "%s  port %d\n", __func__, aio->portnum);
-
-	snd_pcm_set_runtime_buffer(substream, &substream->dma_buffer);
-	runtime->dma_bytes = params_buffer_bytes(params);
-
-	return 0;
-}
-
-static int cygnus_pcm_hw_free(struct snd_soc_component *component,
-			      struct snd_pcm_substream *substream)
-{
-	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
-	struct cygnus_aio_port *aio;
-
-	aio = cygnus_dai_get_dma_data(substream);
-	dev_dbg(asoc_rtd_to_cpu(rtd, 0)->dev, "%s  port %d\n", __func__, aio->portnum);
-
-	snd_pcm_set_runtime_buffer(substream, NULL);
-	return 0;
-}
-
 static int cygnus_pcm_prepare(struct snd_soc_component *component,
 			      struct snd_pcm_substream *substream)
 {
@@ -730,87 +700,19 @@ static snd_pcm_uframes_t cygnus_pcm_pointer(struct snd_soc_component *component,
 	return bytes_to_frames(substream->runtime, res);
 }
 
-static int cygnus_pcm_preallocate_dma_buffer(struct snd_pcm *pcm, int stream)
-{
-	struct snd_pcm_substream *substream = pcm->streams[stream].substream;
-	struct snd_soc_pcm_runtime *rtd = asoc_substream_to_rtd(substream);
-	struct snd_dma_buffer *buf = &substream->dma_buffer;
-	size_t size;
-
-	size = cygnus_pcm_hw.buffer_bytes_max;
-
-	buf->dev.type = SNDRV_DMA_TYPE_DEV;
-	buf->dev.dev = pcm->card->dev;
-	buf->private_data = NULL;
-	buf->area = dma_alloc_coherent(pcm->card->dev, size,
-			&buf->addr, GFP_KERNEL);
-
-	dev_dbg(asoc_rtd_to_cpu(rtd, 0)->dev, "%s: size 0x%zx @ %pK\n",
-				__func__, size, buf->area);
-
-	if (!buf->area) {
-		dev_err(asoc_rtd_to_cpu(rtd, 0)->dev, "%s: dma_alloc failed\n", __func__);
-		return -ENOMEM;
-	}
-	buf->bytes = size;
-
-	return 0;
-}
-
-static void cygnus_dma_free_dma_buffers(struct snd_soc_component *component,
-					struct snd_pcm *pcm)
-{
-	struct snd_pcm_substream *substream;
-	struct snd_dma_buffer *buf;
-
-	substream = pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream;
-	if (substream) {
-		buf = &substream->dma_buffer;
-		if (buf->area) {
-			dma_free_coherent(pcm->card->dev, buf->bytes,
-				buf->area, buf->addr);
-			buf->area = NULL;
-		}
-	}
-
-	substream = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
-	if (substream) {
-		buf = &substream->dma_buffer;
-		if (buf->area) {
-			dma_free_coherent(pcm->card->dev, buf->bytes,
-				buf->area, buf->addr);
-			buf->area = NULL;
-		}
-	}
-}
-
 static int cygnus_dma_new(struct snd_soc_component *component,
 			  struct snd_soc_pcm_runtime *rtd)
 {
+	size_t size = cygnus_pcm_hw.buffer_bytes_max;
 	struct snd_card *card = rtd->card->snd_card;
-	struct snd_pcm *pcm = rtd->pcm;
-	int ret;
 
 	if (!card->dev->dma_mask)
 		card->dev->dma_mask = &cygnus_dma_dmamask;
 	if (!card->dev->coherent_dma_mask)
 		card->dev->coherent_dma_mask = DMA_BIT_MASK(32);
 
-	if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream) {
-		ret = cygnus_pcm_preallocate_dma_buffer(pcm,
-				SNDRV_PCM_STREAM_PLAYBACK);
-		if (ret)
-			return ret;
-	}
-
-	if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream) {
-		ret = cygnus_pcm_preallocate_dma_buffer(pcm,
-				SNDRV_PCM_STREAM_CAPTURE);
-		if (ret) {
-			cygnus_dma_free_dma_buffers(component, pcm);
-			return ret;
-		}
-	}
+	snd_pcm_set_managed_buffer_all(rtd->pcm, SNDRV_DMA_TYPE_DEV,
+				       card->dev, size, size);
 
 	return 0;
 }
@@ -818,13 +720,10 @@ static int cygnus_dma_new(struct snd_soc_component *component,
 static struct snd_soc_component_driver cygnus_soc_platform = {
 	.open		= cygnus_pcm_open,
 	.close		= cygnus_pcm_close,
-	.hw_params	= cygnus_pcm_hw_params,
-	.hw_free	= cygnus_pcm_hw_free,
 	.prepare	= cygnus_pcm_prepare,
 	.trigger	= cygnus_pcm_trigger,
 	.pointer	= cygnus_pcm_pointer,
 	.pcm_construct	= cygnus_dma_new,
-	.pcm_destruct	= cygnus_dma_free_dma_buffers,
 };
 
 int cygnus_soc_platform_register(struct device *dev,