hda-dma: wait for buffer full after starting render

Host DMA should wait for buffer full after starting render
to avoid empty samples at the beginning. Temporary solution
until DMA unified flow will be implemented.

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

Author: tlauda

src/drivers/hda-dma.c

@@ -212,6 +212,14 @@ static int hda_dma_start(struct dma *dma, int channel)
 
 	/* full buffer is copied at startup */
 	p->chan[channel].desc_avail = p->chan[channel].desc_count;
+
+	/* for render let's wait for buffer full */
+	if (p->chan[channel].direction == DMA_DIR_HMEM_TO_LMEM) {
+		do {
+			idelay(PLATFORM_DEFAULT_DELAY);
+			dgcs = host_dma_reg_read(dma, channel, DGCS);
+		} while (!(dgcs & DGCS_BF));
+	}
 out:
 	spin_unlock_irq(&dma->lock, flags);
 	return ret;