linux-kernel - [PATCH 07/15] iio: ti_am335x_adc: Handle set to clear IRQSTATUS

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Date:	Thu, 18 Jul 2013 23:21:18 +0100
From:	Zubair Lutfullah <zubair.lutfullah@...il.com>
To:	jic23@....ac.uk
Cc:	gregkh@...uxfoundation.org, linux-iio@...r.kernel.org,
	linux-kernel@...r.kernel.org, koen@...inion.thruhere.net
Subject: [PATCH 07/15] iio: ti_am335x_adc: Handle set to clear IRQSTATUS

From: Russ Dill <Russ.Dill@...com>

The driver is currently mishandling the IRQSTATUS register by peforming
a read/update/write cycle. The actual functionality of the register is as follows:

Write 0 = No action.
Read 0 = No (enabled) event pending.
Read 1 = Event pending.
Write 1 = Clear (raw) event.

By reading the status and writing it back, the driver is clearing
all pending events, not just the one indicated in the bitmask.

Signed-off-by: Russ Dill <Russ.Dill@...com>
Signed-off-by: Zubair Lutfullah <zubair.lutfullah@...il.com>
---
 drivers/iio/adc/ti_am335x_adc.c |   11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
index b566e6a..1c47818 100644
--- a/drivers/iio/adc/ti_am335x_adc.c
+++ b/drivers/iio/adc/ti_am335x_adc.c
@@ -178,7 +178,7 @@ static irqreturn_t tiadc_irq(int irq, void *private)
 			wake_up_interruptible(&adc_dev->wq_data_avail);
 		}
 		tiadc_writel(adc_dev, REG_IRQSTATUS,
-				(status | IRQENB_FIFO1THRES));
+					IRQENB_FIFO1THRES);
 		return IRQ_HANDLED;
 	} else if ((status &  IRQENB_FIFO1OVRRUN) ||
 			(status &  IRQENB_FIFO1UNDRFLW)) {
@@ -186,12 +186,9 @@ static irqreturn_t tiadc_irq(int irq, void *private)
 		config &= ~(CNTRLREG_TSCSSENB);
 		tiadc_writel(adc_dev,  REG_CTRL, config);
 
-		if (status &  IRQENB_FIFO1UNDRFLW)
-			tiadc_writel(adc_dev,  REG_IRQSTATUS,
-			(status |  IRQENB_FIFO1UNDRFLW));
-		else
-			tiadc_writel(adc_dev,  REG_IRQSTATUS,
-				(status |  IRQENB_FIFO1OVRRUN));
+		tiadc_writel(adc_dev, REG_IRQSTATUS,
+				IRQENB_FIFO1OVRRUN |
+				IRQENB_FIFO1UNDRFLW);
 
 		tiadc_writel(adc_dev,  REG_CTRL,
 			(config |  CNTRLREG_TSCSSENB));
-- 
1.7.9.5

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