[PATCH 4.2 057/258] dmaengine: at_xdmac: fix bug in prep_dma_cyclic

From: Greg Kroah-Hartman
Date: Sun Oct 18 2015 - 00:44:51 EST


4.2-stable review patch. If anyone has any objections, please let me know.

------------------

From: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>

commit e900c30dc1bb0cbc07708e9be1188f531632b2ef upstream.

In cyclic mode, the round chaining has been broken by the introduction
of at_xdmac_queue_desc(): AT_XDMAC_MBR_UBC_NDE is set for all descriptors
excepted for the last one. at_xdmac_queue_desc() has to be called one
more time to chain the last and the first descriptors.

Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
Fixes: 0d0ee751f7f7 ("dmaengine: xdmac: Rework the chaining logic")
Signed-off-by: Vinod Koul <vinod.koul@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/dma/at_xdmac.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -806,10 +806,7 @@ at_xdmac_prep_dma_cyclic(struct dma_chan
list_add_tail(&desc->desc_node, &first->descs_list);
}

- prev->lld.mbr_nda = first->tx_dma_desc.phys;
- dev_dbg(chan2dev(chan),
- "%s: chain lld: prev=0x%p, mbr_nda=%pad\n",
- __func__, prev, &prev->lld.mbr_nda);
+ at_xdmac_queue_desc(chan, prev, first);
first->tx_dma_desc.flags = flags;
first->xfer_size = buf_len;
first->direction = direction;


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