linux-kernel - [PATCH v5 11/18] dmaengine: dma-jz4780: Add missing residue DTC mask

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Date:   Wed, 29 Aug 2018 23:32:53 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Vinod Koul <vkoul@...nel.org>, Ralf Baechle <ralf@...ux-mips.org>,
        Paul Burton <paul.burton@...s.com>
Cc:     od@...c.me, dmaengine@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mips@...ux-mips.org,
        Daniel Silsby <dansilsby@...il.com>,
        Paul Cercueil <paul@...pouillou.net>
Subject: [PATCH v5 11/18] dmaengine: dma-jz4780: Add missing residue DTC mask

From: Daniel Silsby <dansilsby@...il.com>

The 'dtc' word in jz DMA descriptors contains two fields: The
lowest 24 bits are the transfer count, and upper 8 bits are the DOA
offset to next descriptor. The upper 8 bits are now correctly masked
off when computing residue in jz4780_dma_desc_residue(). Note that
reads of the DTCn hardware reg are automatically masked this way.

Signed-off-by: Daniel Silsby <dansilsby@...il.com>
Signed-off-by: Paul Cercueil <paul@...pouillou.net>
Tested-by: Mathieu Malaterre <malat@...ian.org>
---

Notes:
     v2: No change
    
     v3: No change
    
     v4: Add my Signed-off-by
    
     v5: Use GENMASK macro

 drivers/dma/dma-jz4780.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index 3a4d0a4b550d..bd3cecb800c5 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -616,7 +616,8 @@ static size_t jz4780_dma_desc_residue(struct jz4780_dma_chan *jzchan,
 	residue = 0;
 
 	for (i = next_sg; i < desc->count; i++)
-		residue += desc->desc[i].dtc << jzchan->transfer_shift;
+		residue += (desc->desc[i].dtc & GENMASK(23, 0)) <<
+			jzchan->transfer_shift;
 
 	if (next_sg != 0) {
 		count = jz4780_dma_chn_readl(jzdma, jzchan->id,
-- 
2.11.0