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thermal/drivers/tsens: Add timeout to get_temp_tsens_valid

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The function can loop and lock the system if for whatever reason the bit
for the target sensor is NEVER valid. This is the case if a sensor is
disabled by the factory and the valid bit is never reported as actually
valid. Add a timeout check and exit if a timeout occurs. As this is
a very rare condition, handle the timeout only if the first read fails.
While at it also rework the function to improve readability and convert
to poll_timeout generic macro.

Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211007172859.583-1-ansuelsmth@gmail.com
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
This commit is contained in:
Ansuel Smith 2021-10-07 19:28:59 +02:00 committed by Daniel Lezcano
parent 9e5a4fb842
commit d012f9189f
1 changed files with 14 additions and 15 deletions
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29
drivers/thermal/qcom/tsens.c
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@ -603,22 +603,21 @@ int get_temp_tsens_valid(const struct tsens_sensor *s, int *temp)
int ret;
/* VER_0 doesn't have VALID bit */
if (tsens_version(priv) >= VER_0_1) {
ret = regmap_field_read(priv->rf[valid_idx], &valid);
if (ret)
return ret;
while (!valid) {
/* Valid bit is 0 for 6 AHB clock cycles.
* At 19.2MHz, 1 AHB clock is ~60ns.
* We should enter this loop very, very rarely.
*/
ndelay(400);
ret = regmap_field_read(priv->rf[valid_idx], &valid);
if (ret)
return ret;
}
}
if (tsens_version(priv) == VER_0)
goto get_temp;
/* Valid bit is 0 for 6 AHB clock cycles.
* At 19.2MHz, 1 AHB clock is ~60ns.
* We should enter this loop very, very rarely.
* Wait 1 us since it's the min of poll_timeout macro.
* Old value was 400 ns.
*/
ret = regmap_field_read_poll_timeout(priv->rf[valid_idx], valid,
valid, 1, 20 * USEC_PER_MSEC);
if (ret)
return ret;
get_temp:
/* Valid bit is set, OK to read the temperature */
*temp = tsens_hw_to_mC(s, temp_idx);