2015-07-22 14:12:22

by Ludovic Desroches

Subject: [PATCH] dmaengine: at_xdmac: fix bug in prep_dma_cyclic

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 <[email protected]>
Fixes: 0d0ee751f7f7 ("dmaengine: xdmac: Rework the chaining logic")
---
drivers/dma/at_xdmac.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index d51ef6d..df75db4 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -797,10 +797,7 @@ at_xdmac_prep_dma_cyclic(struct dma_chan *chan, dma_addr_t buf_addr,
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;
--
2.2.0

2015-08-19 15:49:51

by Vinod Koul

Subject: Re: [PATCH] dmaengine: at_xdmac: fix bug in prep_dma_cyclic

On Wed, Jul 22, 2015 at 04:12:29PM +0200, Ludovic Desroches wrote:
> 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.

Applied, thanks

--
~Vinod