hda-dma: Fix HDA DMA position regs going out of sync with w_ptr/r_ptr

src/audio/dai-zephyr.c

@@ -1516,6 +1516,9 @@ int dai_zephyr_multi_endpoint_copy(struct dai_data **dd, struct comp_dev *dev,
 			return ret;
 		}
 
+		if (dd[i]->dma->plat_data.caps & SOF_DMA_CAP_HDA)
+			audio_stream_sync_to_hw(&dd[i]->dma_buffer->stream, &stat);
+
 		avail_bytes = MIN(avail_bytes, stat.pending_length);
 		free_bytes = MIN(free_bytes, stat.free);
 	}
@@ -1647,6 +1650,18 @@ int dai_common_copy(struct dai_data *dd, struct comp_dev *dev, pcm_converter_fun
 		return ret;
 	}
 
+	/* HDA DMA Write and Read Position registers are not cleared by hardware on
+	 * dma_stop() or dma_start(). However, the dma_buffer is recreated after a reset
+	 * with its w_ptr and r_ptr set to NULL. The w_ptr and r_ptr must be kept in sync
+	 * with the hardware DMA Write and Read Positions.
+	 * Other types of DMA clear their hardware Read/Write Positions upon dma_stop()
+	 * or dma_start(). Additionally, some DMAs, such as GPDMA, do not populate
+	 * dma_status::write_position and read_position. Therefore, synchronization is
+	 * done here only for HDA DMA.
+	 */
+	if (dd->dma->plat_data.caps & SOF_DMA_CAP_HDA)
+		audio_stream_sync_to_hw(&dd->dma_buffer->stream, &stat);
+
 	avail_bytes = stat.pending_length;
 	free_bytes = stat.free;
 

src/audio/host-zephyr.c

@@ -386,6 +386,23 @@ static uint32_t host_get_copy_bytes_normal(struct host_data *hd, struct comp_dev
 		return 0;
 	}
 
+	/* HDA DMA Write and Read Position registers are not cleared by hardware on
+	 * dma_stop() or dma_start(). However, the dma_buffer is recreated after a reset
+	 * with its w_ptr and r_ptr set to NULL. The w_ptr and r_ptr must be kept in sync
+	 * with the hardware DMA Write and Read Positions.
+	 * Other types of DMA clear their hardware Read/Write Positions upon dma_stop()
+	 * or dma_start(). Additionally, some DMAs, such as GPDMA, do not populate
+	 * dma_status::write_position and read_position. Therefore, synchronization is
+	 * done here only for HDA DMA.
+	 *
+	 * For deep buffers, dma_reload() is called less frequently than consume/produce
+	 * on dma_buffer. Replicate the hardware state of the DMA buffer to the dma_buffer
+	 * struct only when no consume/produce operations on dma_buffer have been called
+	 * since the last dma_reload() (hence hd->partial_size == 0 check here).
+	 */
+	if ((hd->dma->plat_data.caps & SOF_DMA_CAP_HDA) && hd->partial_size == 0)
+		audio_stream_sync_to_hw(&hd->dma_buffer->stream, &dma_stat);
+
 	dma_sample_bytes = hd->config.src_width;
 
 	/* calculate minimum size to copy */

src/include/sof/audio/audio_stream.h

@@ -20,6 +20,7 @@
 #include <sof/compiler_attributes.h>
 #include <rtos/panic.h>
 #include <sof/math/numbers.h>
+#include <sof/lib/dma.h>
 #include <rtos/alloc.h>
 #include <rtos/cache.h>
 #include <ipc/stream.h>
@@ -661,6 +662,35 @@ static inline void audio_stream_consume(struct audio_stream *buffer, uint32_t by
 	buffer->free = buffer->size - buffer->avail;
 }
 
+#ifdef __ZEPHYR__
+/**
+ * Replicates the hardware state of the DMA buffer as a struct audio_stream.
+ * @param stream Stream to update.
+ * @param dma_status DMA buffer hardware state (struct dma_status from Zephyr).
+ */
+static inline void audio_stream_sync_to_hw(struct audio_stream *stream,
+					   const struct dma_status *dma_status)
+{
+	uintptr_t buf_start = (uintptr_t)audio_stream_get_addr(stream);
+
+	/* Note: It is assumed here that dma_status values are reported as bytes. However,
+	 * this is actually platform-specific. Although unlikely, they could be, for example,
+	 * words on some particular platform, and changes should be made here to address
+	 * such case.
+	 */
+
+	assert(dma_status->write_position < audio_stream_get_size(stream));
+	assert(dma_status->read_position < audio_stream_get_size(stream));
+	assert(dma_status->pending_length <= audio_stream_get_size(stream));
+	assert(dma_status->free <= audio_stream_get_size(stream));
+
+	audio_stream_set_wptr(stream, (void *)(buf_start + dma_status->write_position));
+	audio_stream_set_rptr(stream, (void *)(buf_start + dma_status->read_position));
+	audio_stream_set_avail(stream, dma_status->pending_length);
+	audio_stream_set_free(stream, dma_status->free);
+}
+#endif	/* __ZEPHYR__ */
+
 /**
  * Resets the buffer.
  * @param buffer Buffer to reset.