| Message ID | 7fa80c10fcd10d1d47d1bddced2b2cca3ff59ba9.1613131238.git.vilhelm.gray@gmail.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Introduce the Counter character device interface | expand |
On Fri, 12 Feb 2021 21:13:34 +0900 William Breathitt Gray <vilhelm.gray@gmail.com> wrote: > ERANGE is a semantically better error code to return when an argument > value falls outside the supported limit range of a device. #define ERANGE 34 /* Math result not representable */ Not generally applicable to a parameter being out of range despite the name. #define EINVAL 22 /* Invalid argument */ Is probably closer to what we want to describe here. Jonathan > > Cc: Syed Nayyar Waris <syednwaris@gmail.com> > Cc: Fabrice Gasnier <fabrice.gasnier@st.com> > Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> > Cc: Alexandre Torgue <alexandre.torgue@st.com> > Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> > --- > drivers/counter/104-quad-8.c | 6 +++--- > drivers/counter/stm32-lptimer-cnt.c | 2 +- > 2 files changed, 4 insertions(+), 4 deletions(-) > > diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c > index 674263b4d2c4..a2cabb028db0 100644 > --- a/drivers/counter/104-quad-8.c > +++ b/drivers/counter/104-quad-8.c > @@ -154,7 +154,7 @@ static int quad8_count_write(struct counter_device *counter, > > /* Only 24-bit values are supported */ > if (val > 0xFFFFFF) > - return -EINVAL; > + return -ERANGE; > > mutex_lock(&priv->lock); > > @@ -671,7 +671,7 @@ static ssize_t quad8_count_preset_write(struct counter_device *counter, > > /* Only 24-bit values are supported */ > if (preset > 0xFFFFFF) > - return -EINVAL; > + return -ERANGE; > > mutex_lock(&priv->lock); > > @@ -716,7 +716,7 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter, > > /* Only 24-bit values are supported */ > if (ceiling > 0xFFFFFF) > - return -EINVAL; > + return -ERANGE; > > mutex_lock(&priv->lock); > > diff --git a/drivers/counter/stm32-lptimer-cnt.c b/drivers/counter/stm32-lptimer-cnt.c > index daf988e7b208..d5f9d580d06d 100644 > --- a/drivers/counter/stm32-lptimer-cnt.c > +++ b/drivers/counter/stm32-lptimer-cnt.c > @@ -283,7 +283,7 @@ static ssize_t stm32_lptim_cnt_ceiling_write(struct counter_device *counter, > return ret; > > if (ceiling > STM32_LPTIM_MAX_ARR) > - return -EINVAL; > + return -ERANGE; > > priv->ceiling = ceiling; >
On Sun, Feb 14, 2021 at 05:10:21PM +0000, Jonathan Cameron wrote: > On Fri, 12 Feb 2021 21:13:34 +0900 > William Breathitt Gray <vilhelm.gray@gmail.com> wrote: > > > ERANGE is a semantically better error code to return when an argument > > value falls outside the supported limit range of a device. > > #define ERANGE 34 /* Math result not representable */ > > Not generally applicable to a parameter being out of range > despite the name. > #define EINVAL 22 /* Invalid argument */ > Is probably closer to what we want to describe here. > > Jonathan The comment for ERANGE in error-base.h may be terse to a fault. I believe there's a connotation here provided by ERANGE that is absent from EINVAL: primarily that the device buffer is incapable of supporting the desired value (i.e. there is a hardware limitation). This is why strtoul() returns ERANGE if the correct value is outside the range of representable values: the result of the operation is valid in theory (it would be an unsigned integer), but it cannot be returned to the user due to a limitation of the hardware to support that value (e.g. 32-bit registers) [1]. The changes in this patch follow the same logic: these are arguments that are valid in theory (e.g. they are unsigned integers), but the underlying devices are incapable of processing such a value (e.g. the 104-QUAD-8 can only handle 24-bit values). [1] https://stackoverflow.com/a/34981398/1806289 William Breathitt Gray
On 2/12/21 6:13 AM, William Breathitt Gray wrote: > ERANGE is a semantically better error code to return when an argument > value falls outside the supported limit range of a device. > > Cc: Syed Nayyar Waris <syednwaris@gmail.com> > Cc: Fabrice Gasnier <fabrice.gasnier@st.com> > Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> > Cc: Alexandre Torgue <alexandre.torgue@st.com> > Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> > --- Reviewed-by: David Lechner <david@lechnology.com> (I agree with William's assessment that this use of ERANGE is consistent with other uses in the kernel.)
On Tue, 16 Feb 2021 10:26:52 +0900 William Breathitt Gray <vilhelm.gray@gmail.com> wrote: > On Sun, Feb 14, 2021 at 05:10:21PM +0000, Jonathan Cameron wrote: > > On Fri, 12 Feb 2021 21:13:34 +0900 > > William Breathitt Gray <vilhelm.gray@gmail.com> wrote: > > > > > ERANGE is a semantically better error code to return when an argument > > > value falls outside the supported limit range of a device. > > > > #define ERANGE 34 /* Math result not representable */ > > > > Not generally applicable to a parameter being out of range > > despite the name. > > #define EINVAL 22 /* Invalid argument */ > > Is probably closer to what we want to describe here. > > > > Jonathan > > The comment for ERANGE in error-base.h may be terse to a fault. I > believe there's a connotation here provided by ERANGE that is absent > from EINVAL: primarily that the device buffer is incapable of supporting > the desired value (i.e. there is a hardware limitation). > > This is why strtoul() returns ERANGE if the correct value is outside the > range of representable values: the result of the operation is valid in > theory (it would be an unsigned integer), but it cannot be returned to > the user due to a limitation of the hardware to support that value (e.g. > 32-bit registers) [1]. > > The changes in this patch follow the same logic: these are arguments > that are valid in theory (e.g. they are unsigned integers), but the > underlying devices are incapable of processing such a value (e.g. the > 104-QUAD-8 can only handle 24-bit values). > > [1] https://stackoverflow.com/a/34981398/1806289 Its a bit of a stretch, but I can't claim to feel that strongly about this. Jonathan > > William Breathitt Gray
diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c index 674263b4d2c4..a2cabb028db0 100644 --- a/drivers/counter/104-quad-8.c +++ b/drivers/counter/104-quad-8.c @@ -154,7 +154,7 @@ static int quad8_count_write(struct counter_device *counter, /* Only 24-bit values are supported */ if (val > 0xFFFFFF) - return -EINVAL; + return -ERANGE; mutex_lock(&priv->lock); @@ -671,7 +671,7 @@ static ssize_t quad8_count_preset_write(struct counter_device *counter, /* Only 24-bit values are supported */ if (preset > 0xFFFFFF) - return -EINVAL; + return -ERANGE; mutex_lock(&priv->lock); @@ -716,7 +716,7 @@ static ssize_t quad8_count_ceiling_write(struct counter_device *counter, /* Only 24-bit values are supported */ if (ceiling > 0xFFFFFF) - return -EINVAL; + return -ERANGE; mutex_lock(&priv->lock); diff --git a/drivers/counter/stm32-lptimer-cnt.c b/drivers/counter/stm32-lptimer-cnt.c index daf988e7b208..d5f9d580d06d 100644 --- a/drivers/counter/stm32-lptimer-cnt.c +++ b/drivers/counter/stm32-lptimer-cnt.c @@ -283,7 +283,7 @@ static ssize_t stm32_lptim_cnt_ceiling_write(struct counter_device *counter, return ret; if (ceiling > STM32_LPTIM_MAX_ARR) - return -EINVAL; + return -ERANGE; priv->ceiling = ceiling;
ERANGE is a semantically better error code to return when an argument value falls outside the supported limit range of a device. Cc: Syed Nayyar Waris <syednwaris@gmail.com> Cc: Fabrice Gasnier <fabrice.gasnier@st.com> Cc: Maxime Coquelin <mcoquelin.stm32@gmail.com> Cc: Alexandre Torgue <alexandre.torgue@st.com> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com> --- drivers/counter/104-quad-8.c | 6 +++--- drivers/counter/stm32-lptimer-cnt.c | 2 +- 2 files changed, 4 insertions(+), 4 deletions(-)