From fc7be6308364ec52cfe5021c8934b156b00666cf Mon Sep 17 00:00:00 2001 From: Daniel Silsby Date: Wed, 29 Aug 2018 23:32:56 +0200 Subject: [PATCH] dmaengine: dma-jz4780: Further residue status fix [ Upstream commit 83ef4fb7556b6a673f755da670cbacab7e2c7f1b ] 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 Signed-off-by: Paul Cercueil Tested-by: Mathieu Malaterre Signed-off-by: Vinod Koul Signed-off-by: Sasha Levin --- drivers/dma/dma-jz4780.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c index 9878996..edff93a 100644 --- a/drivers/dma/dma-jz4780.c +++ b/drivers/dma/dma-jz4780.c @@ -587,7 +587,7 @@ 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; -- 2.7.4