From 76507fdfc9b629209ae20cd469da2f6d093a507c Mon Sep 17 00:00:00 2001 From: Robert Jarzmik Date: Sun, 7 Aug 2016 21:01:48 +0200 Subject: dmaengine: pxa_dma: fix hotchain corner case In the case where a descriptor is chained on a running channel, and as explained in the comment in the code 10 lines above, the success of the chaining is ensured either if : - the DMA is still running - or if the chained transfer is completed Unfortunately the transfer completness test was done on the descriptor to which the transfer was chained, and not the transfer being chained at the end, ie. hot-chained. This corner case is extremely hard to trigger, as usually the DMA chain is still running, and the first case takes care of returning success of the hot-chaining. It was seen by hot-chaining several "small transfers" to a running "big transfer", not in a real-life usecase but by testing the robustness of the driver. Signed-off-by: Robert Jarzmik Signed-off-by: Vinod Koul --- drivers/dma/pxa_dma.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/dma/pxa_dma.c') diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c index dc7850a422b8..2093e528ae00 100644 --- a/drivers/dma/pxa_dma.c +++ b/drivers/dma/pxa_dma.c @@ -638,7 +638,7 @@ static bool pxad_try_hotchain(struct virt_dma_chan *vc, vd_last_issued = list_entry(vc->desc_issued.prev, struct virt_dma_desc, node); pxad_desc_chain(vd_last_issued, vd); - if (is_chan_running(chan) || is_desc_completed(vd_last_issued)) + if (is_chan_running(chan) || is_desc_completed(vd)) return true; } -- cgit v1.2.3 From 06777c4ec78a43977b63f1d5045def057227c2c5 Mon Sep 17 00:00:00 2001 From: Robert Jarzmik Date: Sun, 7 Aug 2016 21:01:49 +0200 Subject: dmaengine: pxa_dma: fix debug message In a very tight timeframe, the debug message in the transfer completion handler can be misleading, as the completion test report can change just after the message, and the code flow cannot be deduced from the debug message. This is just a cleanup to make debugging easier. Signed-off-by: Robert Jarzmik Signed-off-by: Vinod Koul --- drivers/dma/pxa_dma.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) (limited to 'drivers/dma/pxa_dma.c') diff --git a/drivers/dma/pxa_dma.c b/drivers/dma/pxa_dma.c index 2093e528ae00..3f56f9ca4482 100644 --- a/drivers/dma/pxa_dma.c +++ b/drivers/dma/pxa_dma.c @@ -671,6 +671,7 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id) struct virt_dma_desc *vd, *tmp; unsigned int dcsr; unsigned long flags; + bool vd_completed; dma_cookie_t last_started = 0; BUG_ON(!chan); @@ -681,15 +682,17 @@ static irqreturn_t pxad_chan_handler(int irq, void *dev_id) spin_lock_irqsave(&chan->vc.lock, flags); list_for_each_entry_safe(vd, tmp, &chan->vc.desc_issued, node) { + vd_completed = is_desc_completed(vd); dev_dbg(&chan->vc.chan.dev->device, - "%s(): checking txd %p[%x]: completed=%d\n", - __func__, vd, vd->tx.cookie, is_desc_completed(vd)); + "%s(): checking txd %p[%x]: completed=%d dcsr=0x%x\n", + __func__, vd, vd->tx.cookie, vd_completed, + dcsr); last_started = vd->tx.cookie; if (to_pxad_sw_desc(vd)->cyclic) { vchan_cyclic_callback(vd); break; } - if (is_desc_completed(vd)) { + if (vd_completed) { list_del(&vd->node); vchan_cookie_complete(vd); } else { -- cgit v1.2.3