We have an imx6sx EVB, the audio driver fails to get a valid dma chan and the audio can't work at all on this board, below is the error log: fsl-ssi-dai 202c000.ssi: Missing dma channel for stream: 0 202c000.ssi-nau8822-hifi: ASoC: pcm constructor failed: -22 asoc-simple-card sound: ASoC: can't create pcm 202c000.ssi-nau8822-hifi :-22 Then I checked the usage_count of each dma chan through sysfs, all channels are occupied as below: ubuntu@ubuntu:cd /sys/devices/platform/soc/2000000.bus/20ec000.sdma/dma ubuntu@ubuntu:find . -iname in_use | xargs cat 2 2 2 ... Through debugging, we found the root cause, the crypo/async_tx/async_tx.c calls the dmaengine_get() ahead of registration of dma_device from imx-sdma.c. In the dmaengine_get(), the dmaengine_ref_count will be increased, then in the dma_async_device_register(), the client_count of each chan will be increased. To fix this issue, we could set DMA_PRIVATE to the dma_deivce before registration. Signed-off-by: Hui Wang <hui.wang@xxxxxxxxxxxxx> --- drivers/dma/imx-sdma.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c index 95367a8a81a5..aabe8a8069fb 100644 --- a/drivers/dma/imx-sdma.c +++ b/drivers/dma/imx-sdma.c @@ -2201,6 +2201,7 @@ static int sdma_probe(struct platform_device *pdev) for (i = 0; i < sizeof(*sdma->script_addrs) / sizeof(s32); i++) saddr_arr[i] = -EINVAL; + dma_cap_set(DMA_PRIVATE, sdma->dma_device.cap_mask); dma_cap_set(DMA_SLAVE, sdma->dma_device.cap_mask); dma_cap_set(DMA_CYCLIC, sdma->dma_device.cap_mask); dma_cap_set(DMA_MEMCPY, sdma->dma_device.cap_mask); -- 2.25.1
