| Message ID | 20210907212543.20220-2-ansuelsmth@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Delegated to: | Daniel Lezcano |
| Headers | show |
| Series | [v2,1/2] drivers: thermal: tsens: fix wrong check for tzd in irq handlers | expand |
On Tue, Sep 07, 2021 at 11:25:43PM +0200, 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. > > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> > --- > drivers/thermal/qcom/tsens.c | 40 +++++++++++++++++++++++------------- > 1 file changed, 26 insertions(+), 14 deletions(-) > > diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c > index b1162e566a70..1ff244176beb 100644 > --- a/drivers/thermal/qcom/tsens.c > +++ b/drivers/thermal/qcom/tsens.c > @@ -599,26 +599,38 @@ int get_temp_tsens_valid(const struct tsens_sensor *s, int *temp) > int hw_id = s->hw_id; > u32 temp_idx = LAST_TEMP_0 + hw_id; > u32 valid_idx = VALID_0 + hw_id; > + unsigned long timeout; > u32 valid; > int ret; > > /* VER_0 doesn't have VALID bit */ > - if (tsens_version(priv) >= VER_0_1) { > + if (tsens_version(priv) == VER_0) > + goto get_temp; > + > + ret = regmap_field_read(priv->rf[valid_idx], &valid); > + if (ret || valid) > + goto check_valid; > + > + timeout = jiffies + msecs_to_jiffies(20); > + do { > + /* 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; > - 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 (ret || valid) > + goto check_valid; > + } while (time_before(jiffies, timeout)); > + > + return -ETIMEDOUT; > + > +check_valid: > + /* Check ret of valid bit read */ > + if (ret) > + return ret; > > +get_temp: > /* Valid bit is set, OK to read the temperature */ > *temp = tsens_hw_to_mC(s, temp_idx); I still think that something like this would be clearer than the multiple jumps to 'check_valid': ret = regmap_field_read(priv->rf[valid_idx], &valid); if (ret) return ret; timeout = jiffies + msecs_to_jiffies(20); 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 (time_after(jiffies, timeout)) return -ETIMEDOUT; }; That said, I'm just a random dude, so my opinion isn't really important, as long as the maintainers are happy with the change :)
On 07/09/2021 23:25, 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. > > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> > --- > drivers/thermal/qcom/tsens.c | 40 +++++++++++++++++++++++------------- > 1 file changed, 26 insertions(+), 14 deletions(-) > > diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c > index b1162e566a70..1ff244176beb 100644 > --- a/drivers/thermal/qcom/tsens.c > +++ b/drivers/thermal/qcom/tsens.c > @@ -599,26 +599,38 @@ int get_temp_tsens_valid(const struct tsens_sensor *s, int *temp) > int hw_id = s->hw_id; > u32 temp_idx = LAST_TEMP_0 + hw_id; > u32 valid_idx = VALID_0 + hw_id; > + unsigned long timeout; > u32 valid; > int ret; > > /* VER_0 doesn't have VALID bit */ > - if (tsens_version(priv) >= VER_0_1) { > + if (tsens_version(priv) == VER_0) > + goto get_temp; > + > + ret = regmap_field_read(priv->rf[valid_idx], &valid); > + if (ret || valid) > + goto check_valid; > + > + timeout = jiffies + msecs_to_jiffies(20); Why not use regmap_field_read_poll_timeout() ? > + do { > + /* 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; > - 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 (ret || valid) > + goto check_valid; > + } while (time_before(jiffies, timeout)); > + > + return -ETIMEDOUT; > + > +check_valid: > + /* Check ret of valid bit read */ > + if (ret) > + return ret; > > +get_temp: > /* Valid bit is set, OK to read the temperature */ > *temp = tsens_hw_to_mC(s, temp_idx); > >
On Fri, Sep 17, 2021 at 11:08:15AM +0200, Daniel Lezcano wrote: > On 07/09/2021 23:25, 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. > > > > Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> > > --- > > drivers/thermal/qcom/tsens.c | 40 +++++++++++++++++++++++------------- > > 1 file changed, 26 insertions(+), 14 deletions(-) > > > > diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c > > index b1162e566a70..1ff244176beb 100644 > > --- a/drivers/thermal/qcom/tsens.c > > +++ b/drivers/thermal/qcom/tsens.c > > @@ -599,26 +599,38 @@ int get_temp_tsens_valid(const struct tsens_sensor *s, int *temp) > > int hw_id = s->hw_id; > > u32 temp_idx = LAST_TEMP_0 + hw_id; > > u32 valid_idx = VALID_0 + hw_id; > > + unsigned long timeout; > > u32 valid; > > int ret; > > > > /* VER_0 doesn't have VALID bit */ > > - if (tsens_version(priv) >= VER_0_1) { > > + if (tsens_version(priv) == VER_0) > > + goto get_temp; > > + > > + ret = regmap_field_read(priv->rf[valid_idx], &valid); > > + if (ret || valid) > > + goto check_valid; > > + > > + timeout = jiffies + msecs_to_jiffies(20); > > Why not use regmap_field_read_poll_timeout() ? > Ok will convert this to pool_timeout and send v3. Thx for the review. > > + do { > > + /* 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; > > - 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 (ret || valid) > > + goto check_valid; > > + } while (time_before(jiffies, timeout)); > > + > > + return -ETIMEDOUT; > > + > > +check_valid: > > + /* Check ret of valid bit read */ > > + if (ret) > > + return ret; > > > > +get_temp: > > /* Valid bit is set, OK to read the temperature */ > > *temp = tsens_hw_to_mC(s, temp_idx); > > > > > > > -- > <http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs > > Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook | > <http://twitter.com/#!/linaroorg> Twitter | > <http://www.linaro.org/linaro-blog/> Blog
diff --git a/drivers/thermal/qcom/tsens.c b/drivers/thermal/qcom/tsens.c index b1162e566a70..1ff244176beb 100644 --- a/drivers/thermal/qcom/tsens.c +++ b/drivers/thermal/qcom/tsens.c @@ -599,26 +599,38 @@ int get_temp_tsens_valid(const struct tsens_sensor *s, int *temp) int hw_id = s->hw_id; u32 temp_idx = LAST_TEMP_0 + hw_id; u32 valid_idx = VALID_0 + hw_id; + unsigned long timeout; u32 valid; int ret; /* VER_0 doesn't have VALID bit */ - if (tsens_version(priv) >= VER_0_1) { + if (tsens_version(priv) == VER_0) + goto get_temp; + + ret = regmap_field_read(priv->rf[valid_idx], &valid); + if (ret || valid) + goto check_valid; + + timeout = jiffies + msecs_to_jiffies(20); + do { + /* 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; - 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 (ret || valid) + goto check_valid; + } while (time_before(jiffies, timeout)); + + return -ETIMEDOUT; + +check_valid: + /* Check ret of valid bit read */ + 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. Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com> --- drivers/thermal/qcom/tsens.c | 40 +++++++++++++++++++++++------------- 1 file changed, 26 insertions(+), 14 deletions(-)