From bcfb7465c03a8c62c89da374677df56f6b894d44 Mon Sep 17 00:00:00 2001 From: Ira Snyder Date: Fri, 15 May 2009 14:27:16 -0700 Subject: fsldma: fix infinite loop on multi-descriptor DMA chain completion When creating a DMA transaction with multiple descriptors, the async_tx cookie is set to 0 for each descriptor in the chain, excluding the last descriptor, whose cookie is set to -EBUSY. When fsl_dma_tx_submit() is run, it only assigns a cookie to the first descriptor. All of the remaining descriptors keep their original value, including the last descriptor, which is set to -EBUSY. After the DMA completes, the driver will update the last completed cookie to be -EBUSY, which is an error code instead of a valid cookie. This causes dma_async_is_complete() to always return DMA_IN_PROGRESS. This causes the fsldma driver to never cleanup the queue of link descriptors, and the driver will re-run the DMA transaction on the hardware each time it receives the End-of-Chain interrupt. This causes an infinite loop. With this patch, fsl_dma_tx_submit() is changed to assign a cookie to every descriptor in the chain. The rest of the code then works without problems. Signed-off-by: Ira W. Snyder Signed-off-by: Li Yang --- drivers/dma/fsldma.c | 21 ++++++++++++--------- 1 file changed, 12 insertions(+), 9 deletions(-) (limited to 'drivers/dma') diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c index a4151c3bb78..7313a1ae5f8 100644 --- a/drivers/dma/fsldma.c +++ b/drivers/dma/fsldma.c @@ -313,8 +313,8 @@ static void fsl_chan_toggle_ext_start(struct fsl_dma_chan *fsl_chan, int enable) static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) { - struct fsl_desc_sw *desc = tx_to_fsl_desc(tx); struct fsl_dma_chan *fsl_chan = to_fsl_chan(tx->chan); + struct fsl_desc_sw *desc; unsigned long flags; dma_cookie_t cookie; @@ -322,14 +322,17 @@ static dma_cookie_t fsl_dma_tx_submit(struct dma_async_tx_descriptor *tx) spin_lock_irqsave(&fsl_chan->desc_lock, flags); cookie = fsl_chan->common.cookie; - cookie++; - if (cookie < 0) - cookie = 1; - desc->async_tx.cookie = cookie; - fsl_chan->common.cookie = desc->async_tx.cookie; - - append_ld_queue(fsl_chan, desc); - list_splice_init(&desc->async_tx.tx_list, fsl_chan->ld_queue.prev); + list_for_each_entry(desc, &tx->tx_list, node) { + cookie++; + if (cookie < 0) + cookie = 1; + + desc->async_tx.cookie = cookie; + } + + fsl_chan->common.cookie = cookie; + append_ld_queue(fsl_chan, tx_to_fsl_desc(tx)); + list_splice_init(&tx->tx_list, fsl_chan->ld_queue.prev); spin_unlock_irqrestore(&fsl_chan->desc_lock, flags); -- cgit v1.2.3-70-g09d2