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staging: iio: resolver: ad2s1210: do not use fault register for dummy read

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When reading registers on the AD2S1210 chip, we have to supply a "dummy"
address for the second SPI tx byte so that we don't accidentally write
to a register. This register will be read and the value discarded on the
next regmap read or write call.

Reading the fault register has a side-effect of clearing the faults
so we should not use this register for the dummy read.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-1-ec00746840fc@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
David Lechner
2023-10-05 19:50:18 -05:00
committed by Jonathan Cameron
parent 6eb14ffa18
commit d97d11c70f
1 changed files with 3 additions and 2 deletions
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5
drivers/staging/iio/resolver/ad2s1210.c
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@@ -166,9 +166,10 @@ static int ad2s1210_regmap_reg_read(void *context, unsigned int reg,
st->tx[0] = reg;
/*
* Must be valid register address here otherwise this could write data.
* It doesn't matter which one.
* It doesn't matter which one as long as reading doesn't have side-
* effects.
*/
st->tx[1] = AD2S1210_REG_FAULT;
st->tx[1] = AD2S1210_REG_CONTROL;
ret = spi_sync_transfer(st->sdev, xfers, ARRAY_SIZE(xfers));
if (ret < 0)