Messages in this thread Patch in this message | | | From | Pekka Korpinen <> | Subject | [PATCH v2] iio: dac: ad5446: Fix ad5622_write() return value | Date | Wed, 29 Sep 2021 21:57:55 +0300 |
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On success i2c_master_send() returns the number of bytes written. The call from iio_write_channel_info(), however, expects the return value to be zero on success.
This bug causes incorrect consumption of the sysfs buffer in iio_write_channel_info(). When writing more than two characters to out_voltage0_raw, the ad5446 write handler is called multiple times causing unexpected behavior.
Fixes: 3ec36a2cf0d5 ("iio:ad5446: Add support for I2C based DACs") Signed-off-by: Pekka Korpinen <pekka.korpinen@iki.fi> --- v1->v2: Check against expected result, otherwise -EIO. Add Fixes tag.
A similar bug was fixed for ad5064.c in 2015 - commit 03fe472ef33b ("iio:ad5064: Make sure ad5064_i2c_write() returns 0 on success").
drivers/iio/dac/ad5446.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/iio/dac/ad5446.c b/drivers/iio/dac/ad5446.c index 488ec69967d6..e50718422411 100644 --- a/drivers/iio/dac/ad5446.c +++ b/drivers/iio/dac/ad5446.c @@ -531,8 +531,15 @@ static int ad5622_write(struct ad5446_state *st, unsigned val) { struct i2c_client *client = to_i2c_client(st->dev); __be16 data = cpu_to_be16(val); + int ret; + + ret = i2c_master_send(client, (char *)&data, sizeof(data)); + if (ret < 0) + return ret; + if (ret != sizeof(data)) + return -EIO; - return i2c_master_send(client, (char *)&data, sizeof(data)); + return 0; } /* -- 2.33.0
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