From 26a2dfdeb9b93b82735d2227a118afa0ddd912dd Mon Sep 17 00:00:00 2001 From: Xiang Wang Date: Tue, 18 Jun 2013 14:55:59 +0800 Subject: [PATCH] dma: mmp_pdma: clear DRCMR when free a phy channel In mmp pdma, phy channels are allocated/freed dynamically. The mapping from DMA request to DMA channel number in DRCMR should be cleared when a phy channel is freed. Otherwise conflicts will happen when: 1. A is using channel 2 and free it after finished, but A still maps to channel 2 in DRCMR of A. 2. Now another one B gets channel 2. So B maps to channel 2 too in DRCMR of B. In the datasheet, it is described that "Do not map two active requests to the same channel since it produces unpredictable results" and we can observe that during test. Signed-off-by: Xiang Wang Signed-off-by: Vinod Koul --- drivers/dma/mmp_pdma.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c index b1a2600..9a32f2d 100644 --- a/drivers/dma/mmp_pdma.c +++ b/drivers/dma/mmp_pdma.c @@ -252,10 +252,16 @@ static void mmp_pdma_free_phy(struct mmp_pdma_chan *pchan) { struct mmp_pdma_device *pdev = to_mmp_pdma_dev(pchan->chan.device); unsigned long flags; + u32 reg; if (!pchan->phy) return; + /* clear the channel mapping in DRCMR */ + reg = pchan->phy->vchan->drcmr; + reg = ((reg < 64) ? 0x0100 : 0x1100) + ((reg & 0x3f) << 2); + writel(0, pchan->phy->base + reg); + spin_lock_irqsave(&pdev->phy_lock, flags); pchan->phy->vchan = NULL; pchan->phy = NULL; -- 2.7.4