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authorNicolas Ferre <nicolas.ferre@atmel.com>2012-04-16 14:46:30 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-05-07 08:56:33 -0700
commit17a766decb63b6fe4c43c06069b92b4958d7a642 (patch)
parent7a47462902d03c6e4d3412a5b703069f4dd13c44 (diff)
dmaengine: at_hdmac: remove clear-on-read in atc_dostart()
commit ed8b0d67f33518a16c6b2450fe5ebebf180c2d04 upstream. This loop on EBCISR register was designed to clear IRQ sources before enabling a DMA channel. This register is clear-on-read so a race condition can appear if another channel is already active and has just finished its transfer. Removing this read on EBCISR is fixing the issue as there is no case where an IRQ could be pending: we already make sure that this register is drained at probe() time and during resume. Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
1 files changed, 0 insertions, 4 deletions
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 9e9318abc510..10c63495ea00 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -237,10 +237,6 @@ static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first)
- /* clear any pending interrupt */
- while (dma_readl(atdma, EBCISR))
- cpu_relax();
channel_writel(atchan, SADDR, 0);
channel_writel(atchan, DADDR, 0);
channel_writel(atchan, CTRLA, 0);