From f04cd40701deace2efb9edd7120e59366bda2118 Mon Sep 17 00:00:00 2001 From: Ira Snyder Date: Thu, 3 Mar 2011 07:54:58 +0000 Subject: fsldma: fix controller lockups Enabling poisoning in the dmapool API quickly showed that the DMA controller was fetching descriptors that should not have been in use. This has caused intermittent controller lockups during testing. I have been unable to figure out the exact set of conditions which cause this to happen. However, I believe it is related to the driver using the hardware registers to track whether the controller is busy or not. The code can incorrectly decide that the hardware is idle due to lag between register writes and the hardware actually becoming busy. To fix this, the driver has been reworked to explicitly track the state of the hardware, rather than try to guess what it is doing based on the register values. This has passed dmatest with 10 threads per channel, 100000 iterations per thread several times without error. Previously, this would fail within a few seconds. Signed-off-by: Ira W. Snyder Signed-off-by: Dan Williams --- drivers/dma/fsldma.h | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/dma/fsldma.h') diff --git a/drivers/dma/fsldma.h b/drivers/dma/fsldma.h index 49189dacd5f..9cb5aa57c67 100644 --- a/drivers/dma/fsldma.h +++ b/drivers/dma/fsldma.h @@ -148,6 +148,7 @@ struct fsldma_chan { int id; /* Raw id of this channel */ struct tasklet_struct tasklet; u32 feature; + bool idle; /* DMA controller is idle */ void (*toggle_ext_pause)(struct fsldma_chan *fsl_chan, int enable); void (*toggle_ext_start)(struct fsldma_chan *fsl_chan, int enable); -- cgit v1.2.3