dai: capture buffer should also be flushed from cache

Writes back capture dma buffer from cache to sram.
We stopped to invalidate buffer shared between DMAs,
so this change is needed to avoid glitches due to
the potential data eviction during cache miss.

Signed-off-by: Tomasz Lauda <tomasz.lauda@linux.intel.com>

Author: tlauda

src/audio/dai.c

@@ -444,14 +444,16 @@ static int dai_prepare(struct comp_dev *dev)
 
 	/* initialise buffers */
 	if (dev->params.direction == SOF_IPC_STREAM_PLAYBACK) {
-
-		/* write back buffer contents from cache for playback */
 		dma_buffer = list_first_item(&dev->bsource_list,
 			struct comp_buffer, sink_list);
-
-		dcache_writeback_region(dma_buffer->addr, dma_buffer->size);
+	} else {
+		dma_buffer = list_first_item(&dev->bsink_list,
+			struct comp_buffer, source_list);
 	}
 
+	/* write back buffer contents from cache */
+	dcache_writeback_region(dma_buffer->addr, dma_buffer->size);
+
 	/* dma reconfig not required if XRUN handling */
 	if (dd->xrun) {
 		/* after prepare, we have recovered from xrun */