[PATCH] dmaengine: at_xdmac: fix slave configuration issue

[Ludovic Desroches]

When doing the slave configuration, an error is returned if the maxburst
value is not supported. The bug comes from the fact that we always check
the maxburst for both directions but in the case of an unidirectional
channel, only one is set.

Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
Cc: <stable at vger.kernel.org> # 3.19 and later
---
 drivers/dma/at_xdmac.c | 97 +++++++++++++++++++++++++++-----------------------
 1 file changed, 52 insertions(+), 45 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index d9891d3..30e161b 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -501,54 +501,61 @@ static int at_xdmac_set_slave_config(struct dma_chan *chan,
 	u8 dwidth;
 	int csize;
 
-	atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG] =
-		AT91_XDMAC_DT_PERID(atchan->perid)
-		| AT_XDMAC_CC_DAM_INCREMENTED_AM
-		| AT_XDMAC_CC_SAM_FIXED_AM
-		| AT_XDMAC_CC_DIF(atchan->memif)
-		| AT_XDMAC_CC_SIF(atchan->perif)
-		| AT_XDMAC_CC_SWREQ_HWR_CONNECTED
-		| AT_XDMAC_CC_DSYNC_PER2MEM
-		| AT_XDMAC_CC_MBSIZE_SIXTEEN
-		| AT_XDMAC_CC_TYPE_PER_TRAN;
-	csize = at_xdmac_csize(sconfig->src_maxburst);
-	if (csize < 0) {
-		dev_err(chan2dev(chan), "invalid src maxburst value\n");
-		return -EINVAL;
-	}
-	atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG] |= AT_XDMAC_CC_CSIZE(csize);
-	dwidth = ffs(sconfig->src_addr_width) - 1;
-	atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG] |= AT_XDMAC_CC_DWIDTH(dwidth);
-
-
-	atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG] =
-		AT91_XDMAC_DT_PERID(atchan->perid)
-		| AT_XDMAC_CC_DAM_FIXED_AM
-		| AT_XDMAC_CC_SAM_INCREMENTED_AM
-		| AT_XDMAC_CC_DIF(atchan->perif)
-		| AT_XDMAC_CC_SIF(atchan->memif)
-		| AT_XDMAC_CC_SWREQ_HWR_CONNECTED
-		| AT_XDMAC_CC_DSYNC_MEM2PER
-		| AT_XDMAC_CC_MBSIZE_SIXTEEN
-		| AT_XDMAC_CC_TYPE_PER_TRAN;
-	csize = at_xdmac_csize(sconfig->dst_maxburst);
-	if (csize < 0) {
-		dev_err(chan2dev(chan), "invalid src maxburst value\n");
-		return -EINVAL;
+	if (sconfig->src_addr) {
+		atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG] =
+			AT91_XDMAC_DT_PERID(atchan->perid)
+			| AT_XDMAC_CC_DAM_INCREMENTED_AM
+			| AT_XDMAC_CC_SAM_FIXED_AM
+			| AT_XDMAC_CC_DIF(atchan->memif)
+			| AT_XDMAC_CC_SIF(atchan->perif)
+			| AT_XDMAC_CC_SWREQ_HWR_CONNECTED
+			| AT_XDMAC_CC_DSYNC_PER2MEM
+			| AT_XDMAC_CC_MBSIZE_SIXTEEN
+			| AT_XDMAC_CC_TYPE_PER_TRAN;
+		csize = at_xdmac_csize(sconfig->src_maxburst);
+		if (csize < 0) {
+			dev_err(chan2dev(chan), "invalid src maxburst value\n");
+			return -EINVAL;
+		}
+		atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG] |= AT_XDMAC_CC_CSIZE(csize);
+		dwidth = ffs(sconfig->src_addr_width) - 1;
+		atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG] |= AT_XDMAC_CC_DWIDTH(dwidth);
+		/* Src addr is needed to configure the link list descriptor. */
+		atchan->per_src_addr = sconfig->src_addr;
+
+		dev_dbg(chan2dev(chan),
+			"%s: cfg[dev2mem]=0x%08x, per_src_addr=0x%08x\n",
+			__func__, atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG],
+			atchan->per_src_addr);
 	}
-	atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG] |= AT_XDMAC_CC_CSIZE(csize);
-	dwidth = ffs(sconfig->dst_addr_width) - 1;
-	atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG] |= AT_XDMAC_CC_DWIDTH(dwidth);
 
-	/* Src and dst addr are needed to configure the link list descriptor. */
-	atchan->per_src_addr = sconfig->src_addr;
-	atchan->per_dst_addr = sconfig->dst_addr;
+	if (sconfig->dst_addr) {
+		atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG] =
+			AT91_XDMAC_DT_PERID(atchan->perid)
+			| AT_XDMAC_CC_DAM_FIXED_AM
+			| AT_XDMAC_CC_SAM_INCREMENTED_AM
+			| AT_XDMAC_CC_DIF(atchan->perif)
+			| AT_XDMAC_CC_SIF(atchan->memif)
+			| AT_XDMAC_CC_SWREQ_HWR_CONNECTED
+			| AT_XDMAC_CC_DSYNC_MEM2PER
+			| AT_XDMAC_CC_MBSIZE_SIXTEEN
+			| AT_XDMAC_CC_TYPE_PER_TRAN;
+		csize = at_xdmac_csize(sconfig->dst_maxburst);
+		if (csize < 0) {
+			dev_err(chan2dev(chan), "invalid src maxburst value\n");
+			return -EINVAL;
+		}
+		atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG] |= AT_XDMAC_CC_CSIZE(csize);
+		dwidth = ffs(sconfig->dst_addr_width) - 1;
+		atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG] |= AT_XDMAC_CC_DWIDTH(dwidth);
+		/* Dst addr is needed to configure the link list descriptor. */
+		atchan->per_dst_addr = sconfig->dst_addr;
 
-	dev_dbg(chan2dev(chan),
-		"%s: cfg[dev2mem]=0x%08x, cfg[mem2dev]=0x%08x, per_src_addr=0x%08x, per_dst_addr=0x%08x\n",
-		__func__, atchan->cfg[AT_XDMAC_DEV_TO_MEM_CFG],
-		atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG],
-		atchan->per_src_addr, atchan->per_dst_addr);
+		dev_dbg(chan2dev(chan),
+			"%s: cfg[mem2dev]=0x%08x, per_dst_addr=0x%08x\n",
+			__func__, atchan->cfg[AT_XDMAC_MEM_TO_DEV_CFG],
+			atchan->per_dst_addr);
+	}
 
 	return 0;
 }
-- 
2.2.0