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iio: adc: ad7380: fix SPI offload trigger rate

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Add a special case to double the SPI offload trigger rate when all
channels of a single-ended chip are enabled in a buffered read.

The single-ended chips in the AD738x family can only do simultaneous
sampling of half their channels and have a multiplexer to allow reading
the other half. To comply with the IIO definition of sampling_frequency,
we need to trigger twice as often when the sequencer is enabled to so
that both banks can be read in a single sample period.

Fixes: bbeaec81a0 ("iio: ad7380: add support for SPI offload")
Signed-off-by: David Lechner <dlechner@baylibre.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
David Lechner
2025-09-19 15:50:34 -05:00
committed by Jonathan Cameron
parent 9b45744bf0
commit 632757312d
1 changed files with 8 additions and 0 deletions
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8
drivers/iio/adc/ad7380.c
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@@ -1227,6 +1227,14 @@ static int ad7380_offload_buffer_postenable(struct iio_dev *indio_dev)
if (ret) if (ret)
return ret; return ret;
/*
* When the sequencer is required to read all channels, we need to
* trigger twice per sample period in order to read one complete set
* of samples.
*/
if (st->seq)
config.periodic.frequency_hz *= 2;
ret = spi_offload_trigger_enable(st->offload, st->offload_trigger, &config); ret = spi_offload_trigger_enable(st->offload, st->offload_trigger, &config);
if (ret) if (ret)
spi_unoptimize_message(&st->offload_msg); spi_unoptimize_message(&st->offload_msg);