linux-kernel - [PATCH 21/21] dmaengine: edma: Simplify and optimize ccerr interrupt handler

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Date:	Thu, 10 Sep 2015 11:37:50 +0300
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	<vinod.koul@...el.com>, <nsekhar@...com>, <linux@....linux.org.uk>
CC:	<olof@...om.net>, <arnd@...db.de>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<dmaengine@...r.kernel.org>
Subject: [PATCH 21/21] 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@...com>
---
 drivers/dma/edma.c | 64 ++++++++++++++++++++----------------------------------
 1 file changed, 23 insertions(+), 41 deletions(-)

diff --git a/drivers/dma/edma.c b/drivers/dma/edma.c
index f1e898525ae6..81302daf687c 100644
--- a/drivers/dma/edma.c
+++ b/drivers/dma/edma.c
@@ -1625,6 +1625,7 @@ static irqreturn_t dma_ccerr_handler(int irq, void *data)
 	int i;
 	int ctlr;
 	unsigned int cnt = 0;
+	unsigned int val;
 
 	ctlr = ecc->id;
 	if (ctlr < 0)
@@ -1637,54 +1638,35 @@ static irqreturn_t dma_ccerr_handler(int irq, void *data)
 
 	while (1) {
 		int j = -1;
-		if (edma_read_array(ecc, EDMA_EMR, 0))
+		if ((val = edma_read_array(ecc, EDMA_EMR, 0)))
 			j = 0;
-		else if (edma_read_array(ecc, EDMA_EMR, 1))
+		else if ((val = 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++) {
+			unsigned long emr = val;
+
+			dev_dbg(ecc->dev, "EMR%d 0x%08x\n", j, 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]);
 			}
+		} else if ((val = edma_read(ecc, EDMA_QEMR))) {
+			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);
+		} else if ((val = edma_read(ecc, EDMA_CCERR))) {
+			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++;
-- 
2.5.1

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