From 852534744c2d35626a604f128ff0b8ec12805591 Mon Sep 17 00:00:00 2001 From: Christofer Jonason Date: Wed, 4 Mar 2026 10:07:27 +0100 Subject: [PATCH] iio: adc: xilinx-xadc: Fix sequencer mode in postdisable for dual mux MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit xadc_postdisable() unconditionally sets the sequencer to continuous mode. For dual external multiplexer configurations this is incorrect: simultaneous sampling mode is required so that ADC-A samples through the mux on VAUX[0-7] while ADC-B simultaneously samples through the mux on VAUX[8-15]. In continuous mode only ADC-A is active, so VAUX[8-15] channels return incorrect data. Since postdisable is also called from xadc_probe() to set the initial idle state, the wrong sequencer mode is active from the moment the driver loads. The preenable path already uses xadc_get_seq_mode() which returns SIMULTANEOUS for dual mux. Fix postdisable to do the same. Fixes: bdc8cda1d010 ("iio:adc: Add Xilinx XADC driver") Cc: stable@vger.kernel.org Signed-off-by: Christofer Jonason Reviewed-by: Andy Shevchenko Reviewed-by: Nuno Sá Reviewed-by: Salih Erim Signed-off-by: Jonathan Cameron --- drivers/iio/adc/xilinx-xadc-core.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/iio/adc/xilinx-xadc-core.c b/drivers/iio/adc/xilinx-xadc-core.c index e257c1b94a5f..3980dfacbcd7 100644 --- a/drivers/iio/adc/xilinx-xadc-core.c +++ b/drivers/iio/adc/xilinx-xadc-core.c @@ -817,6 +817,7 @@ static int xadc_postdisable(struct iio_dev *indio_dev) { struct xadc *xadc = iio_priv(indio_dev); unsigned long scan_mask; + int seq_mode; int ret; int i; @@ -824,6 +825,12 @@ static int xadc_postdisable(struct iio_dev *indio_dev) for (i = 0; i < indio_dev->num_channels; i++) scan_mask |= BIT(indio_dev->channels[i].scan_index); + /* + * Use the correct sequencer mode for the idle state: simultaneous + * mode for dual external mux configurations, continuous otherwise. + */ + seq_mode = xadc_get_seq_mode(xadc, scan_mask); + /* Enable all channels and calibration */ ret = xadc_write_adc_reg(xadc, XADC_REG_SEQ(0), scan_mask & 0xffff); if (ret) @@ -834,11 +841,11 @@ static int xadc_postdisable(struct iio_dev *indio_dev) return ret; ret = xadc_update_adc_reg(xadc, XADC_REG_CONF1, XADC_CONF1_SEQ_MASK, - XADC_CONF1_SEQ_CONTINUOUS); + seq_mode); if (ret) return ret; - return xadc_power_adc_b(xadc, XADC_CONF1_SEQ_CONTINUOUS); + return xadc_power_adc_b(xadc, seq_mode); } static int xadc_preenable(struct iio_dev *indio_dev)