From: Ansuel Smith ansuelsmth@gmail.com
[ Upstream commit d012f9189fda0f3a1b303780ba0bbc7298d0d349 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/thermal/qcom/tsens.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-)
diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c index b1162e566a707..99a8d9f3e03ca 100644 --- a/drivers/thermal/qcom/tsens.c +++ b/drivers/thermal/qcom/tsens.c @@ -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);