ASoC: dmaengine-pcm: Make requesting the DMA channel at PCM open optional

Refactor the dmaengine PCM library to allow the DMA channel to be requested
before opening a PCM substream. snd_dmaengine_pcm_open() now expects a DMA
channel instead of a filter function and filter parameter as its parameters.
snd_dmaengine_pcm_close() is updated to not release the DMA channel. This allows
a dmaengine based PCM driver to request its channels before the substream is
opened.

The patch also introduces two new functions, snd_dmaengine_pcm_open_request_chan()
and snd_dmaengine_pcm_close_release_chan(), which have the same signature and
behaviour of the old snd_dmaengine_pcm_{open,close}() and internally use the new
variants of these functions. All users of snd_dmaengine_pcm_{open,close}() are
updated to use snd_dmaengine_pcm_open_request_chan() and
snd_dmaengine_pcm_close_release_chan().

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Tested-by: Stephen Warren <swarren@nvidia.com>
Tested-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/atmel/atmel-pcm-dma.c b/sound/soc/atmel/atmel-pcm-dma.c
index bb07989..1d38fd0 100644
--- a/sound/soc/atmel/atmel-pcm-dma.c
+++ b/sound/soc/atmel/atmel-pcm-dma.c
@@ -155,7 +155,7 @@
 	if (ssc->pdev)
 		sdata = ssc->pdev->dev.platform_data;
 
-	ret = snd_dmaengine_pcm_open(substream, filter, sdata);
+	ret = snd_dmaengine_pcm_open_request_chan(substream, filter, sdata);
 	if (ret) {
 		pr_err("atmel-pcm: dmaengine pcm open failed\n");
 		return -EINVAL;
@@ -171,7 +171,7 @@
 
 	return 0;
 err:
-	snd_dmaengine_pcm_close(substream);
+	snd_dmaengine_pcm_close_release_chan(substream);
 	return ret;
 }
 
@@ -197,7 +197,7 @@
 
 static struct snd_pcm_ops atmel_pcm_ops = {
 	.open		= atmel_pcm_open,
-	.close		= snd_dmaengine_pcm_close,
+	.close		= snd_dmaengine_pcm_close_release_chan,
 	.ioctl		= snd_pcm_lib_ioctl,
 	.hw_params	= atmel_pcm_hw_params,
 	.prepare	= atmel_pcm_dma_prepare,