Re: [PATCH] hwmon: (tmp108) Fix initial conversion delay and wait until ready

[sashiko-bot@kernel.org]

> In tmp108_common_probe(), the driver only adds the 30 ms conversion delay
> (TMP108_CONVERSION_TIME_MS) to ready_time if the sensor was previously in
> TMP108_MODE_SHUTDOWN. However, the TMP108 hardware defaults to continuous
> conversion mode (TMP108_MODE_CONTINUOUS) upon power-on reset, including
> immediately after enabling the vcc supply regulator during probe, while
> the temperature register retains its power-on reset value of 0x0000 (0°C)
> until the first conversion completes. Because the initial mode is not
> shutdown, the delay is bypassed and early reads via thermal zone
> registration or sysfs before the first conversion finishes return an
> uninitialized 0°C reading.
> 
> In addition, returning -EAGAIN from tmp108_read() while waiting for a
> conversion to complete after probe or resume can trigger an unnecessary
> tight retry loop in callers or fail initial reads.
> 
> Unconditionally set ready_time to TMP108_CONVERSION_TIME_MS ahead in
> tmp108_common_probe(), track ready_time as ktime_t, and wait for the
> remaining conversion time in tmp108_read() using usleep_range() instead
> of returning -EAGAIN.
> 
> Reported-by: Sashiko <sashiko-bot@kernel.org>
> Fixes: 66e1c9171339 ("hwmon: Add Texas Instruments TMP108 temperature sensor driver.")
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261031034834.1079813-1-linux@roeck-us.net?part=1