Using USB audio gadget in capture mode with an non blocking API may
result in getting uninitialized memory samples. That ensure that the
memory is initialized to 0 when the stream is prepared.
Signed-off-by: Lionel Koenig <lionel.koenig@xxxxxxxxx>
---
drivers/usb/gadget/function/u_audio.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index 7ec6a996af26..6d708494ca77 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -317,6 +317,14 @@ static int uac_pcm_open(struct snd_pcm_substream *substream)
return 0;
}
+static int uac_pcm_prepare(struct snd_pcm_substream *substream)
+{
+ struct snd_pcm_runtime *runtime = substream->runtime;
+
+ memset(runtime->dma_area, 0, runtime->dma_bytes);
+ return 0;
+}
+
/* ALSA cries without these function pointers */
static int uac_pcm_null(struct snd_pcm_substream *substream)
{
@@ -331,7 +339,7 @@ static const struct snd_pcm_ops uac_pcm_ops = {
.hw_free = uac_pcm_hw_free,
.trigger = uac_pcm_trigger,
.pointer = uac_pcm_pointer,
- .prepare = uac_pcm_null,
+ .prepare = uac_pcm_prepare,
};
static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)
--
2.24.0.393.g34dc348eaf-goog
