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[02/12] dma: mmp_pdma: clear DRCMR when free a phy channel

Message ID 1375870770-14263-3-git-send-email-zonque@gmail.com (mailing list archive)
State New, archived
Headers show

Commit Message

Daniel Mack Aug. 7, 2013, 10:19 a.m. UTC 
From: Xiang Wang <wangx@marvell.com>

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 <wangx@marvell.com>
---
 drivers/dma/mmp_pdma.c | 6 ++++++
 1 file changed, 6 insertions(+)
diff mbox

Patch

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index 226158d..2844eaf 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;