iio: adc: ad7124: fix chip ID mismatch

commit 96f9ab0d5933c1c00142dd052f259fce0bc3ced2 upstream.

The ad7124_soft_reset() function has the assumption that the chip will
assert the "power-on reset" bit in the STATUS register after a software
reset without any delay. The POR bit =0 is used to check if the chip
initialization is done.

A chip ID mismatch probe error appears intermittently when the probe
continues too soon and the ID register does not contain the expected
value.

Fix by adding a 200us delay after the software reset command is issued.

Fixes: b3af341bbd96 ("iio: adc: Add ad7124 support")
Signed-off-by: Dumitru Ceclan <dumitru.ceclan@analog.com>
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://patch.msgid.link/20240731-ad7124-fix-v1-1-46a76aa4b9be@analog.com
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/iio/adc/ad7124.c b/drivers/iio/adc/ad7124.c
index 19ab7d7251bcb24833d515e3cf7e108a886afdf0..99d1288e66828366d2065240e600a86e091daddd 100644 (file)
--- a/drivers/iio/adc/ad7124.c
+++ b/drivers/iio/adc/ad7124.c
@@ -500,6 +500,7 @@ static int ad7124_soft_reset(struct ad7124_state *st)
        if (ret < 0)
                return ret;
 
+       fsleep(200);
        timeout = 100;
        do {
                ret = ad_sd_read_reg(&st->sd, AD7124_STATUS, 1, &readval);