From mboxrd@z Thu Jan 1 00:00:00 1970 From: shawnguo@kernel.org (Shawn Guo) Date: Thu, 15 Dec 2016 22:03:37 +0800 Subject: [PATCH 3/3] dma: zx: fix residue calculation In-Reply-To: <1481810617-7650-1-git-send-email-shawnguo@kernel.org> References: <1481810617-7650-1-git-send-email-shawnguo@kernel.org> Message-ID: <1481810617-7650-3-git-send-email-shawnguo@kernel.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org From: Shawn Guo The dma residue is defined as the free space to end of transfer buffer, which could be multiple segments chained together. So the residue calculation in zx_dma_tx_status() works for both slave_sg and cyclic case. But unfortunately, the 'index' is wrong. It should plus one, because the current segment is already occupied and shouldn't be counted into free space. This fixes the HDMI audio noise issue we see on ZX296718 with SPDIF interface. Signed-off-by: Shawn Guo --- drivers/dma/zx_dma.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/dma/zx_dma.c b/drivers/dma/zx_dma.c index 33155c6816cc..42ff3e66c1e1 100644 --- a/drivers/dma/zx_dma.c +++ b/drivers/dma/zx_dma.c @@ -365,7 +365,8 @@ static enum dma_status zx_dma_tx_status(struct dma_chan *chan, bytes = 0; clli = zx_dma_get_curr_lli(p); - index = (clli - ds->desc_hw_lli) / sizeof(struct zx_desc_hw); + index = (clli - ds->desc_hw_lli) / + sizeof(struct zx_desc_hw) + 1; for (; index < ds->desc_num; index++) { bytes += ds->desc_hw[index].src_x; /* end of lli */ -- 1.9.1