[PATCH v2 13/17] dmaengine: dma-jz4780: Further residue status fix

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Daniel Silsby <dansilsby@xxxxxxxxx>

Func jz4780_dma_desc_residue() expects the index to the next hw
descriptor as its last parameter. Caller func jz4780_dma_tx_status(),
however, applied modulus before passing it. When the current hw
descriptor was last in the list, the index passed became zero.

The resulting excess of reported residue especially caused problems
with cyclic DMA transfer clients, i.e. ALSA AIC audio output, which
rely on this for determining current DMA location within buffer.

Combined with the recent and related residue-reporting fixes, spurious
ALSA audio underruns on jz4770 hardware are now fixed.

Signed-off-by: Daniel Silsby <dansilsby@xxxxxxxxx>
Tested-by: Mathieu Malaterre <malat@xxxxxxxxxx>
---
 drivers/dma/dma-jz4780.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

 v2: No change

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 78849131c81d..b9db539a5b34 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -651,7 +651,7 @@ static enum dma_status jz4780_dma_tx_status(struct dma_chan *chan,
 					to_jz4780_dma_desc(vdesc), 0);
 	} else if (cookie == jzchan->desc->vdesc.tx.cookie) {
 		txstate->residue = jz4780_dma_desc_residue(jzchan, jzchan->desc,
-			  (jzchan->curr_hwdesc + 1) % jzchan->desc->count);
+					jzchan->curr_hwdesc + 1);
 	} else
 		txstate->residue = 0;
 
-- 
2.11.0

--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Device Tree Compilter]     [Device Tree Spec]     [Linux Driver Backports]     [Video for Linux]     [Linux USB Devel]     [Linux PCI Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [XFree86]     [Yosemite Backpacking]


  Powered by Linux