Patchwork [v3,9/9] fsldma: make halt behave nicely on all supported controllers

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Submitter Ira Snyder
Date March 3, 2011, 5:55 p.m.
Message ID <1299174901-16762-10-git-send-email-iws@ovro.caltech.edu>
Download mbox | patch
Permalink /patch/85316/
State Accepted
Delegated to: Kumar Gala
Headers show

Comments

Ira Snyder - March 3, 2011, 5:55 p.m.
The original dma_halt() function set the CA (channel abort) bit on both
the 83xx and 85xx controllers. This is incorrect on the 83xx, where this
bit means TEM (transfer error mask) instead. The 83xx doesn't support
channel abort, so we only do this operation on 85xx.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
---
 drivers/dma/fsldma.c |   19 ++++++++++++++++---
 1 files changed, 16 insertions(+), 3 deletions(-)

Patch

diff --git a/drivers/dma/fsldma.c b/drivers/dma/fsldma.c
index d300de4..8670a50 100644
--- a/drivers/dma/fsldma.c
+++ b/drivers/dma/fsldma.c
@@ -221,13 +221,26 @@  static void dma_halt(struct fsldma_chan *chan)
 	u32 mode;
 	int i;
 
+	/* read the mode register */
 	mode = DMA_IN(chan, &chan->regs->mr, 32);
-	mode |= FSL_DMA_MR_CA;
-	DMA_OUT(chan, &chan->regs->mr, mode, 32);
 
-	mode &= ~(FSL_DMA_MR_CS | FSL_DMA_MR_EMS_EN | FSL_DMA_MR_CA);
+	/*
+	 * The 85xx controller supports channel abort, which will stop
+	 * the current transfer. On 83xx, this bit is the transfer error
+	 * mask bit, which should not be changed.
+	 */
+	if ((chan->feature & FSL_DMA_IP_MASK) == FSL_DMA_IP_85XX) {
+		mode |= FSL_DMA_MR_CA;
+		DMA_OUT(chan, &chan->regs->mr, mode, 32);
+
+		mode &= ~FSL_DMA_MR_CA;
+	}
+
+	/* stop the DMA controller */
+	mode &= ~(FSL_DMA_MR_CS | FSL_DMA_MR_EMS_EN);
 	DMA_OUT(chan, &chan->regs->mr, mode, 32);
 
+	/* wait for the DMA controller to become idle */
 	for (i = 0; i < 100; i++) {
 		if (dma_is_idle(chan))
 			return;