linux-kernel - [PATCH] iio: at91-sama5d2_adc: fix iio_triggered_buffer

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Message-ID: <20191023082508.17583-1-alexandru.ardelean@analog.com>
Date:   Wed, 23 Oct 2019 11:25:08 +0300
From:   Alexandru Ardelean <alexandru.ardelean@...log.com>
To:     <linux-iio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
CC:     <ludovic.desroches@...rochip.com>, <jic23@...nel.org>,
        <nicolas.ferre@...rochip.com>, <alexandre.belloni@...tlin.com>,
        <knaack.h@....de>, <lars@...afoo.de>, <pmeerw@...erw.net>,
        Alexandru Ardelean <alexandru.ardelean@...log.com>
Subject: [PATCH] iio: at91-sama5d2_adc: fix iio_triggered_buffer_{predisable,postenable} positions

The iio_triggered_buffer_{predisable,postenable} functions attach/detach
poll functions.

The iio_triggered_buffer_postenable() should be called first to attach the
poll function, and then the driver can init the data to be triggered.

Similarly, iio_triggered_buffer_predisable() should be called last to first
disable the data (to be triggered) and then the poll function should be
detached.

For this driver, the predisable & postenable hooks are also need to take
into consideration the touchscreen, so the hooks need to be put in places
that avoid the code for that cares about it.

Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>
---
 drivers/iio/adc/at91-sama5d2_adc.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
index e1850f3d5cf3..ac3e5c4c9840 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -889,20 +889,24 @@ static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
 	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
 		return -EINVAL;
 
+	ret = iio_triggered_buffer_postenable(indio_dev);
+	if (ret)
+		return ret;
+
 	/* we continue with the triggered buffer */
 	ret = at91_adc_dma_start(indio_dev);
 	if (ret) {
 		dev_err(&indio_dev->dev, "buffer postenable failed\n");
+		iio_triggered_buffer_predisable(indio_dev);
 		return ret;
 	}
 
-	return iio_triggered_buffer_postenable(indio_dev);
+	return 0;
 }
 
 static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
-	int ret;
 	u8 bit;
 
 	/* check if we are disabling triggered buffer or the touchscreen */
@@ -916,13 +920,8 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 	if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
 		return -EINVAL;
 
-	/* continue with the triggered buffer */
-	ret = iio_triggered_buffer_predisable(indio_dev);
-	if (ret < 0)
-		dev_err(&indio_dev->dev, "buffer predisable failed\n");
-
 	if (!st->dma_st.dma_chan)
-		return ret;
+		goto out;
 
 	/* if we are using DMA we must clear registers and end DMA */
 	dmaengine_terminate_sync(st->dma_st.dma_chan);
@@ -949,7 +948,9 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
 
 	/* read overflow register to clear possible overflow status */
 	at91_adc_readl(st, AT91_SAMA5D2_OVER);
-	return ret;
+
+out:
+	return iio_triggered_buffer_predisable(indio_dev);
 }
 
 static const struct iio_buffer_setup_ops at91_buffer_setup_ops = {
-- 
2.20.1