From: Peter Ujfalusi <peter.ujfalusi@xxxxxxxxxxxxxxx>
Buffers allocated with snd_dma_alloc_pages() will have DMA direction
DMA_BIDIRECTIONAL. The trace data memory is only used for one DMA
direction: DMA_FROM_DEVICE, DMA only writes there, never reads.
We also need to do a sync before accessing (reading with CPU) from the
trace data buffer to copy it to user space.
Note: snd_dma_buffer_sync() is also used for normal playback and capture
streams to make sure that the data is available for the DMA or CPU.
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@xxxxxxxxxxxxxxx>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxxxxxxxxxxx>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
sound/soc/sof/trace.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/sound/soc/sof/trace.c b/sound/soc/sof/trace.c
index 104388c551cb..ea8e4506d02e 100644
--- a/sound/soc/sof/trace.c
+++ b/sound/soc/sof/trace.c
@@ -320,6 +320,13 @@ static ssize_t sof_dfsentry_trace_read(struct file *file, char __user *buffer,
if (count > avail)
count = avail;
+ /*
+ * make sure that all trace data is available for the CPU as the trace
+ * data buffer might be allocated from non consistent memory.
+ * Note: snd_dma_buffer_sync() is called for normal audio playback and
+ * capture streams also.
+ */
+ snd_dma_buffer_sync(&sdev->dmatb, SNDRV_DMA_SYNC_CPU);
/* copy available trace data to debugfs */
rem = copy_to_user(buffer, ((u8 *)(dfse->buf) + lpos), count);
if (rem)
@@ -464,8 +471,9 @@ int snd_sof_init_trace(struct snd_sof_dev *sdev)
}
/* allocate trace data buffer */
- ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV_SG, sdev->dev,
- DMA_BUF_SIZE_FOR_TRACE, &sdev->dmatb);
+ ret = snd_dma_alloc_dir_pages(SNDRV_DMA_TYPE_DEV_SG, sdev->dev,
+ DMA_FROM_DEVICE, DMA_BUF_SIZE_FOR_TRACE,
+ &sdev->dmatb);
if (ret < 0) {
dev_err(sdev->dev,
"error: can't alloc buffer for trace %d\n", ret);
--
2.30.2
