| Message ID | 20211007172859.583-1-ansuelsmth@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Daniel Lezcano |
| Headers | show |
| Series | [RESEND,v3] drivers: thermal: tsens: add timeout to get_temp_tsens_valid | expand |
On Thu 07 Oct 10:28 PDT 2021, Ansuel Smith wrote: > 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. > Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org> Regards, Bjorn > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> > --- > 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 b1162e566a70..99a8d9f3e03c 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); > > -- > 2.32.0 >
diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c index b1162e566a70..99a8d9f3e03c 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);
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> --- drivers/thermal/qcom/tsens.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-)