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>

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 7aa58d2048923721d7448464120515137ecc961f..445fdf8116959e91bff7469bf45c6283e057b198 100644 (file)
--- 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);