From d97d11c70f25726fc21b2b2f1a26e16ac96a8ccf Mon Sep 17 00:00:00 2001 From: David Lechner Date: Thu, 5 Oct 2023 19:50:18 -0500 Subject: [PATCH] staging: iio: resolver: ad2s1210: do not use fault register for dummy read 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 Link: https://lore.kernel.org/r/20231005-ad2s1210-mainline-v4-1-ec00746840fc@baylibre.com Signed-off-by: Jonathan Cameron --- drivers/staging/iio/resolver/ad2s1210.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c index 67d8af0dd7ae2..8fbde9517fe94 100644 --- a/drivers/staging/iio/resolver/ad2s1210.c +++ b/drivers/staging/iio/resolver/ad2s1210.c @@ -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) -- 2.30.2