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dmaengine: at_hdmac: remove clear-on-read in atc_dostart() 

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>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>
This commit is contained in:
Nicolas Ferre 2012-04-16 14:46:30 +02:00 committed by Vinod Koul
parent d04525ed03
commit ed8b0d67f3
1 changed files with 0 additions and 4 deletions
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4
drivers/dma/at_hdmac.c
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@ -221,10 +221,6 @@ static void atc_dostart(struct at_dma_chan *atchan, struct at_desc *first)
vdbg_dump_regs(atchan);
/* 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);