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[3/7] usb: gadget: u_audio: update hw_ptr in iso_complete after data copied

Message ID 20180621152252.8313-4-erosca@de.adit-jv.com (mailing list archive)
State New, archived
Headers show

Commit Message

Eugeniu Rosca June 21, 2018, 3:22 p.m. UTC 
From: Joshua Frkuska <joshua_frkuska@mentor.com>

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@mentor.com>
Signed-off-by: Eugeniu Rosca <erosca@de.adit-jv.com>
---
 drivers/usb/gadget/function/u_audio.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
diff mbox

Patch

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__);