From 138ef0185177a6d221d24b6aa8f12d867fbbef90 Mon Sep 17 00:00:00 2001 From: Ira Snyder Date: Tue, 19 May 2009 15:42:13 -0700 Subject: [PATCH] fsldma: fix "DMA halt timeout!" errors When using the DMA controller from multiple threads at the same time, it is possible to get lots of "DMA halt timeout!" errors printed to the kernel log. This occurs due to a race between fsl_dma_memcpy_issue_pending() and the interrupt handler, fsl_dma_chan_do_interrupt(). Both call the fsl_chan_xfer_ld_queue() function, which does not protect against concurrent accesses to dma_halt() and dma_start(). The existing spinlock is moved to cover the dma_halt() and dma_start() functions. Testing shows that the "DMA halt timeout!" errors disappear. Signed-off-by: Ira W. Snyder Signed-off-by: Li Yang --- drivers/dma/fsldma.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c index 391b1bd7098b..a4151c3bb78b 100644 --- a/drivers/dma/fsldma.c +++ b/drivers/dma/fsldma.c @@ -598,15 +598,16 @@ static void fsl_chan_xfer_ld_queue(struct fsl_dma_chan *fsl_chan) dma_addr_t next_dest_addr; unsigned long flags; + spin_lock_irqsave(&fsl_chan->desc_lock, flags); + if (!dma_is_idle(fsl_chan)) - return; + goto out_unlock; dma_halt(fsl_chan); /* If there are some link descriptors * not transfered in queue. We need to start it. */ - spin_lock_irqsave(&fsl_chan->desc_lock, flags); /* Find the first un-transfer desciptor */ for (ld_node = fsl_chan->ld_queue.next; @@ -617,8 +618,6 @@ static void fsl_chan_xfer_ld_queue(struct fsl_dma_chan *fsl_chan) fsl_chan->common.cookie) == DMA_SUCCESS); ld_node = ld_node->next); - spin_unlock_irqrestore(&fsl_chan->desc_lock, flags); - if (ld_node != &fsl_chan->ld_queue) { /* Get the ld start address from ld_queue */ next_dest_addr = to_fsl_desc(ld_node)->async_tx.phys; @@ -630,6 +629,9 @@ static void fsl_chan_xfer_ld_queue(struct fsl_dma_chan *fsl_chan) set_cdar(fsl_chan, 0); set_ndar(fsl_chan, 0); } + +out_unlock: + spin_unlock_irqrestore(&fsl_chan->desc_lock, flags); } /** -- 2.39.5