hwmon: (sht4x) Fix EREMOTEIO errors
authorDavid Mosberger-Tang <davidm@egauge.net>
Sat, 20 Nov 2021 21:28:56 +0000 (21:28 +0000)
committerGuenter Roeck <linux@roeck-us.net>
Sat, 20 Nov 2021 22:44:25 +0000 (14:44 -0800)
commit0e4190d762ef2609111507e1b9553a166436f556
treed2d522ef5f68aca3debc672842850333a492a0c5
parent214f525255069a55b4664842c68bc15b2ee049f0
hwmon: (sht4x) Fix EREMOTEIO errors

Per datasheet, SHT4x may need up to 8.2ms for a "high repeatability"
measurement to complete.  Attempting to read the result too early
triggers a NAK which then causes an EREMOTEIO error.

This behavior has been confirmed with a logic analyzer while running
the I2C bus at only 40kHz.  The low frequency precludes any
signal-integrity issues, which was also confirmed by the absence of
any CRC8 errors.  In this configuration, a NAK occurred on any read
that followed the measurement command within less than 8.2ms.

Signed-off-by: David Mosberger-Tang <davidm@egauge.net>
Link: https://lore.kernel.org/r/20211120212849.2300854-2-davidm@egauge.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
drivers/hwmon/sht4x.c