linux-kernel - [PATCH] iio: adc: stm32-adc: dma transfers cleanup

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Message-ID: <20201105142941.27301-1-olivier.moysan@st.com>
Date:   Thu, 5 Nov 2020 15:29:41 +0100
From:   Olivier Moysan <olivier.moysan@...com>
To:     <jic23@...nel.org>, <knaack.h@....de>, <lars@...afoo.de>,
        <pmeerw@...erw.net>, <alexandre.torgue@...com>,
        <fabrice.gasnier@...com>, <olivier.moysan@...com>
CC:     <linux-iio@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: [PATCH] iio: adc: stm32-adc: dma transfers cleanup

- Remove processing related to DMA in irq handler as this
data transfer is managed directly in DMA callback.
- Update comment in stm32_adc_set_watermark() function.

Signed-off-by: Olivier Moysan <olivier.moysan@...com>
---
 drivers/iio/adc/stm32-adc.c | 29 ++++++-----------------------
 1 file changed, 6 insertions(+), 23 deletions(-)

diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
index b3f31f147347..08be826f1462 100644
--- a/drivers/iio/adc/stm32-adc.c
+++ b/drivers/iio/adc/stm32-adc.c
@@ -1310,7 +1310,7 @@ static int stm32_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
 	 * dma cyclic transfers are used, buffer is split into two periods.
 	 * There should be :
 	 * - always one buffer (period) dma is working on
-	 * - one buffer (period) driver can push with iio_trigger_poll().
+	 * - one buffer (period) driver can push data.
 	 */
 	watermark = min(watermark, val * (unsigned)(sizeof(u16)));
 	adc->rx_buf_sz = min(rx_buf_sz, watermark * 2 * adc->num_conv);
@@ -1573,31 +1573,14 @@ static irqreturn_t stm32_adc_trigger_handler(int irq, void *p)
 
 	dev_dbg(&indio_dev->dev, "%s bufi=%d\n", __func__, adc->bufi);
 
-	if (!adc->dma_chan) {
-		/* reset buffer index */
-		adc->bufi = 0;
-		iio_push_to_buffers_with_timestamp(indio_dev, adc->buffer,
-						   pf->timestamp);
-	} else {
-		int residue = stm32_adc_dma_residue(adc);
-
-		while (residue >= indio_dev->scan_bytes) {
-			u16 *buffer = (u16 *)&adc->rx_buf[adc->bufi];
-
-			iio_push_to_buffers_with_timestamp(indio_dev, buffer,
-							   pf->timestamp);
-			residue -= indio_dev->scan_bytes;
-			adc->bufi += indio_dev->scan_bytes;
-			if (adc->bufi >= adc->rx_buf_sz)
-				adc->bufi = 0;
-		}
-	}
-
+	/* reset buffer index */
+	adc->bufi = 0;
+	iio_push_to_buffers_with_timestamp(indio_dev, adc->buffer,
+					   pf->timestamp);
 	iio_trigger_notify_done(indio_dev->trig);
 
 	/* re-enable eoc irq */
-	if (!adc->dma_chan)
-		stm32_adc_conv_irq_enable(adc);
+	stm32_adc_conv_irq_enable(adc);
 
 	return IRQ_HANDLED;
 }
-- 
2.17.1