linux-kernel - [PATCH] dmaengine: edma: Re-evaluate errors when ccerr is triggered w/o error event

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Date:	Tue, 10 May 2016 13:40:54 +0300
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	<vinod.koul@...el.com>, <dan.j.williams@...el.com>
CC:	<rogerq@...com>, <dmaengine@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <nsekhar@...com>,
	<tony@...mide.com>
Subject: [PATCH] dmaengine: edma: Re-evaluate errors when ccerr is triggered w/o error event

When the ccerr handler is called but the error registers indicate no error
events we need to command eDMA to re-evaluate the errors. Otherwise we can
receive flood of error interrupts.

Reported-by: Roger Quadros <rogerq@...com>
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
---
 drivers/dma/edma.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 10f9b992b927..7c76b558cf82 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -1540,8 +1540,17 @@ static irqreturn_t dma_ccerr_handler(int irq, void *data)
 
 	dev_vdbg(ecc->dev, "dma_ccerr_handler\n");
 
-	if (!edma_error_pending(ecc))
+	if (!edma_error_pending(ecc)) {
+		/*
+		 * The registers indicate no pending error event but the irq
+		 * handler has been called.
+		 * Ask eDMA to re-evaluate the error registers.
+		 */
+		dev_err(ecc->dev, "%s: Error interrupt without error event!\n",
+			__func__);
+		edma_write(ecc, EDMA_EEVAL, 1);
 		return IRQ_NONE;
+	}
 
 	while (1) {
 		/* Event missed register(s) */
-- 
2.8.2