From: Joshua Frkuska <joshua_frkuska@xxxxxxxxxx>
In u_audio_iso_complete, the runtime hw_ptr is updated before the
data is actually copied over to/from the buffer/dma area. When
ALSA uses this hw_ptr, the data may not actually be available to
be used. This causes trash/stale audio to play/record. This
patch updates the hw_ptr after the data has been copied to avoid
this.
Fixes: 132fcb460839 ("usb: gadget: Add Audio Class 2.0 Driver")
Signed-off-by: Joshua Frkuska <joshua_frkuska@xxxxxxxxxx>
Signed-off-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
---
drivers/usb/gadget/function/u_audio.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/gadget/function/u_audio.c b/drivers/usb/gadget/function/u_audio.c
index c0a65e110fc9..4c6df7130891 100644
--- a/drivers/usb/gadget/function/u_audio.c
+++ b/drivers/usb/gadget/function/u_audio.c
@@ -143,7 +143,6 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
update_alsa = true;
hw_ptr = prm->hw_ptr;
- prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;
spin_unlock_irqrestore(&prm->lock, flags);
@@ -168,6 +167,11 @@ static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)
}
}
+ spin_lock_irqsave(&prm->lock, flags);
+ /* update hw_ptr after data is copied to memory */
+ prm->hw_ptr = (hw_ptr + req->actual) % prm->dma_bytes;
+ spin_unlock_irqrestore(&prm->lock, flags);
+
exit:
if (usb_ep_queue(ep, req, GFP_ATOMIC))
dev_err(uac->card->dev, "%d Error!\n", __LINE__);
--
2.17.0
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