From ed8b0d67f33518a16c6b2450fe5ebebf180c2d04 Mon Sep 17 00:00:00 2001
From: Nicolas Ferre <nicolas.ferre@atmel.com>
Date: Mon, 16 Apr 2012 14:46:30 +0200
Subject: 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>
---
 drivers/dma/at_hdmac.c | 4 ----
 1 file changed, 4 deletions(-)

(limited to 'drivers/dma')

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 7aa58d204892..445fdf811695 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -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);
-- 
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