From e4402a129faca71ddd160d89ef7750da0ce2d6c4 Mon Sep 17 00:00:00 2001
From: Peter Ujfalusi <peter.ujfalusi@ti.com>
Date: Wed, 14 Oct 2015 14:43:03 +0300
Subject: [PATCH] dmaengine: edma: Simplify and optimize ccerr interrupt
 handler

No need to run through the bits in QEMR and CCERR events since they will
not trigger any action, so just clearing the errors there is fine.
In case of the missed event the loop can be optimized so we spend less time
to handle the event.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
---
 drivers/dma/edma.c | 80 ++++++++++++++++++++--------------------------
 1 file changed, 34 insertions(+), 46 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index 84b98a01993a..d105d1ae0f13 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -1640,9 +1640,10 @@ static inline bool edma_error_pending(struct edma_cc *ecc)
 static irqreturn_t dma_ccerr_handler(int irq, void *data)
 {
 	struct edma_cc *ecc = data;
-	int i;
+	int i, j;
 	int ctlr;
 	unsigned int cnt = 0;
+	unsigned int val;
 
 	ctlr = ecc->id;
 	if (ctlr < 0)
@@ -1654,57 +1655,44 @@ static irqreturn_t dma_ccerr_handler(int irq, void *data)
 		return IRQ_NONE;
 
 	while (1) {
-		int j = -1;
+		/* Event missed register(s) */
+		for (j = 0; j < 2; j++) {
+			unsigned long emr;
 
-		if (edma_read_array(ecc, EDMA_EMR, 0))
-			j = 0;
-		else if (edma_read_array(ecc, EDMA_EMR, 1))
-			j = 1;
-		if (j >= 0) {
-			dev_dbg(ecc->dev, "EMR%d %08x\n", j,
-				edma_read_array(ecc, EDMA_EMR, j));
-			for (i = 0; i < 32; i++) {
+			val = edma_read_array(ecc, EDMA_EMR, j);
+			if (!val)
+				continue;
+
+			dev_dbg(ecc->dev, "EMR%d 0x%08x\n", j, val);
+			emr = val;
+			for (i = find_next_bit(&emr, 32, 0); i < 32;
+			     i = find_next_bit(&emr, 32, i + 1)) {
 				int k = (j << 5) + i;
 
-				if (edma_read_array(ecc, EDMA_EMR, j) &
-							BIT(i)) {
-					/* Clear the corresponding EMR bits */
-					edma_write_array(ecc, EDMA_EMCR, j,
+				/* Clear the corresponding EMR bits */
+				edma_write_array(ecc, EDMA_EMCR, j, BIT(i));
+				/* Clear any SER */
+				edma_shadow0_write_array(ecc, SH_SECR, j,
 							 BIT(i));
-					/* Clear any SER */
-					edma_shadow0_write_array(ecc, SH_SECR,
-								 j, BIT(i));
-					edma_error_handler(&ecc->slave_chans[k]);
-				}
-			}
-		} else if (edma_read(ecc, EDMA_QEMR)) {
-			dev_dbg(ecc->dev, "QEMR %02x\n",
-				edma_read(ecc, EDMA_QEMR));
-			for (i = 0; i < 8; i++) {
-				if (edma_read(ecc, EDMA_QEMR) & BIT(i)) {
-					/* Clear the corresponding IPR bits */
-					edma_write(ecc, EDMA_QEMCR, BIT(i));
-					edma_shadow0_write(ecc, SH_QSECR,
-							   BIT(i));
-
-					/* NOTE:  not reported!! */
-				}
-			}
-		} else if (edma_read(ecc, EDMA_CCERR)) {
-			dev_dbg(ecc->dev, "CCERR %08x\n",
-				edma_read(ecc, EDMA_CCERR));
-			/* FIXME:  CCERR.BIT(16) ignored!  much better
-			 * to just write CCERRCLR with CCERR value...
-			 */
-			for (i = 0; i < 8; i++) {
-				if (edma_read(ecc, EDMA_CCERR) & BIT(i)) {
-					/* Clear the corresponding IPR bits */
-					edma_write(ecc, EDMA_CCERRCLR, BIT(i));
-
-					/* NOTE:  not reported!! */
-				}
+				edma_error_handler(&ecc->slave_chans[k]);
 			}
 		}
+
+		val = edma_read(ecc, EDMA_QEMR);
+		if (val) {
+			dev_dbg(ecc->dev, "QEMR 0x%02x\n", val);
+			/* Not reported, just clear the interrupt reason. */
+			edma_write(ecc, EDMA_QEMCR, val);
+			edma_shadow0_write(ecc, SH_QSECR, val);
+		}
+
+		val = edma_read(ecc, EDMA_CCERR);
+		if (val) {
+			dev_warn(ecc->dev, "CCERR 0x%08x\n", val);
+			/* Not reported, just clear the interrupt reason. */
+			edma_write(ecc, EDMA_CCERRCLR, val);
+		}
+
 		if (!edma_error_pending(ecc))
 			break;
 		cnt++;