linux-kernel - [PATCH 10/10] dma: imx-sdma: clear channel0 interrupt bit in irq routine

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Date:	Mon, 16 May 2016 17:37:58 +0900
From:	Jiada Wang <jiada_wang@...tor.com>
To:	<vinod.koul@...el.com>, <dan.j.williams@...el.com>
CC:	<dmaengine@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<george_davis@...tor.com>, <jiada_wang@...tor.com>
Subject: [PATCH 10/10] dma: imx-sdma: clear channel0 interrupt bit in irq routine

When SDMA channel0 timeouts, even it's disabled in error path,
but sometimes we still see its interrupt bit be asserted,
which causes irq routine be triggered continuously because
no one else clears this bit.

This commit clears channel0 interrupt as well in irq routine,
so that even channel0 timeouts, it won't cause irq storm,
also adds lock to prevent irq routine to clear this bit when
sdma_run_channel0() is busy checking it.

Signed-off-by: Jiada Wang <jiada_wang@...tor.com>
---
 drivers/dma/imx-sdma.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 8b20bf4..ca1c984 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -768,12 +768,16 @@ static void sdma_tasklet(unsigned long data)
 static irqreturn_t sdma_int_handler(int irq, void *dev_id)
 {
 	struct sdma_engine *sdma = dev_id;
-	unsigned long stat;
+	unsigned long stat, flags;
+
+	spin_lock_irqsave(&sdma->channel_0_lock, flags);
 
 	stat = readl_relaxed(sdma->regs + SDMA_H_INTR);
+	writel_relaxed(stat, sdma->regs + SDMA_H_INTR);
 	/* not interested in channel 0 interrupts */
 	stat &= ~1;
-	writel_relaxed(stat, sdma->regs + SDMA_H_INTR);
+
+	spin_unlock_irqrestore(&sdma->channel_0_lock, flags);
 
 	while (stat) {
 		int channel = fls(stat) - 1;
-- 
2.4.5