ALSA: compress: make use of runtime buffer for copy

Default copy function uses kmalloc to allocate buffers, lets check
if the runtime buffers are setup before making this allocations.
This can be useful if the buffers are dma buffers.
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Acked-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/core/compress_offload.c

@@ -171,7 +171,8 @@ static int snd_compr_free(struct inode *inode, struct file *f)
 	}
 
 	data->stream.ops->free(&data->stream);
-	kfree(data->stream.runtime->buffer);
+	if (!data->stream.runtime->dma_buffer_p)
+		kfree(data->stream.runtime->buffer);
 	kfree(data->stream.runtime);
 	kfree(data);
 	return 0;
@@ -505,7 +506,7 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream,
 		struct snd_compr_params *params)
 {
 	unsigned int buffer_size;
-	void *buffer;
+	void *buffer = NULL;
 
 	buffer_size = params->buffer.fragment_size * params->buffer.fragments;
 	if (stream->ops->copy) {
@@ -514,7 +515,18 @@ static int snd_compr_allocate_buffer(struct snd_compr_stream *stream,
 		 * the data from core
 		 */
 	} else {
-		buffer = kmalloc(buffer_size, GFP_KERNEL);
+		if (stream->runtime->dma_buffer_p) {
+
+			if (buffer_size > stream->runtime->dma_buffer_p->bytes)
+				dev_err(&stream->device->dev,
+						"Not enough DMA buffer");
+			else
+				buffer = stream->runtime->dma_buffer_p->area;
+
+		} else {
+			buffer = kmalloc(buffer_size, GFP_KERNEL);
+		}
+
 		if (!buffer)
 			return -ENOMEM;
 	}