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From:   <Eugen.Hristev@microchip.com>
To:     <jic23@kernel.org>, <linux-iio@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>
CC:     <Ludovic.Desroches@microchip.com>, <Eugen.Hristev@microchip.com>
Subject: [PATCH v2 1/3] iio: adc: at91-sama5d2_adc: fix differential channels
 in triggered mode
Thread-Topic: [PATCH v2 1/3] iio: adc: at91-sama5d2_adc: fix differential
 channels in triggered mode
Thread-Index: AQHVygn64v98utrynU+d9NR0RxZ56Q==
Date:   Mon, 13 Jan 2020 12:07:09 +0000
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From: Eugen Hristev <eugen.hristev@microchip.com>

The differential channels require writing the channel offset register (COR)=
.
Otherwise they do not work in differential mode.
The configuration of COR is missing in triggered mode.

Fixes: 5e1a1da0f8c9 ("iio: adc: at91-sama5d2_adc: add hw trigger and buffer=
 support")
Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
---
Changes in v2:
- moved to the start of the list

 drivers/iio/adc/at91-sama5d2_adc.c | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama=
5d2_adc.c
index e1850f3..2a6950a 100644
--- a/drivers/iio/adc/at91-sama5d2_adc.c
+++ b/drivers/iio/adc/at91-sama5d2_adc.c
@@ -723,6 +723,7 @@ static int at91_adc_configure_trigger(struct iio_trigge=
r *trig, bool state)
=20
 	for_each_set_bit(bit, indio->active_scan_mask, indio->num_channels) {
 		struct iio_chan_spec const *chan =3D at91_adc_chan_get(indio, bit);
+		u32 cor;
=20
 		if (!chan)
 			continue;
@@ -732,6 +733,20 @@ static int at91_adc_configure_trigger(struct iio_trigg=
er *trig, bool state)
 			continue;
=20
 		if (state) {
+			cor =3D at91_adc_readl(st, AT91_SAMA5D2_COR);
+
+			if (chan->differential)
+				cor |=3D (BIT(chan->channel) |
+					BIT(chan->channel2)) <<
+					AT91_SAMA5D2_COR_DIFF_OFFSET;
+			else
+				cor &=3D ~(BIT(chan->channel) <<
+				       AT91_SAMA5D2_COR_DIFF_OFFSET);
+
+			at91_adc_writel(st, AT91_SAMA5D2_COR, cor);
+		}
+
+		if (state) {
 			at91_adc_writel(st, AT91_SAMA5D2_CHER,
 					BIT(chan->channel));
 			/* enable irq only if not using DMA */
--=20
2.7.4