From: Xiang Wang Date: Tue, 18 Jun 2013 06:55:59 +0000 (+0800) Subject: dma: mmp_pdma: clear DRCMR when free a phy channel X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=26a2dfdeb9b93b82735d2227a118afa0ddd912dd;p=linux-beck.git 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 --- diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c index b1a260002cf8..9a32f2d174b0 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;