[PATCH] iio: lidar: return -EIO on invalid signal

[PATCH] iio: lidar: return -EIO on invalid signal

[Matt Ranostay]

Returning zero from the measurment function has the side effect of
corrupting the triggered buffer readings, better to use -EIO than a
zero measurement reading.

Signed-off-by: Matt Ranostay <mranostay@gmail.com>
---
 drivers/iio/proximity/pulsedlight-lidar-lite-v2.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
index 961f9f99..359beac 100644
--- a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
+++ b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
@@ -130,10 +130,10 @@ static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
 		if (ret < 0)
 			break;
 
-		/* return 0 since laser is likely pointed out of range */
+		/* return -EIO since laser is likely pointed out of range */
 		if (ret & LIDAR_REG_STATUS_INVALID) {
 			*reg = 0;
-			ret = 0;
+			ret = -EIO;
 			break;
 		}
 
-- 
1.9.1

Re: [PATCH] iio: lidar: return -EIO on invalid signal

[Jonathan Cameron]

On 25/10/15 23:07, Matt Ranostay wrote:
> Returning zero from the measurment function has the side effect of
> corrupting the triggered buffer readings, better to use -EIO than a
> zero measurement reading.
When you say 'corrupting' what do you mean?  As far as I can quickly see
it will give a spurious 0 distance when it really means a long distance.
Is that what you are referring to?

Jonathan
> 
> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
> ---
>  drivers/iio/proximity/pulsedlight-lidar-lite-v2.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
> index 961f9f99..359beac 100644
> --- a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
> +++ b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
> @@ -130,10 +130,10 @@ static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
>  		if (ret < 0)
>  			break;
>  
> -		/* return 0 since laser is likely pointed out of range */
> +		/* return -EIO since laser is likely pointed out of range */
>  		if (ret & LIDAR_REG_STATUS_INVALID) {
>  			*reg = 0;
> -			ret = 0;
> +			ret = -EIO;
>  			break;
>  		}
>  
> 

Re: [PATCH] iio: lidar: return -EIO on invalid signal

[Matt Ranostay]

Actually the INVALID status happens even it isn't out of range
sometimes roughly once every second or two. This can be from an
invalid second signal return path and etc..

So there are spurious zero readings from the triggered buffer, and
warning messages in the kernel log.

Thanks,

Matt

On Sat, Oct 31, 2015 at 2:29 AM, Jonathan Cameron <jic23@kernel.org> wrote:
> On 25/10/15 23:07, Matt Ranostay wrote:
>> Returning zero from the measurment function has the side effect of
>> corrupting the triggered buffer readings, better to use -EIO than a
>> zero measurement reading.
> When you say 'corrupting' what do you mean?  As far as I can quickly see
> it will give a spurious 0 distance when it really means a long distance.
> Is that what you are referring to?
>
> Jonathan
>>
>> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
>> ---
>>  drivers/iio/proximity/pulsedlight-lidar-lite-v2.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
>> index 961f9f99..359beac 100644
>> --- a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
>> +++ b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
>> @@ -130,10 +130,10 @@ static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
>>               if (ret < 0)
>>                       break;
>>
>> -             /* return 0 since laser is likely pointed out of range */
>> +             /* return -EIO since laser is likely pointed out of range */
>>               if (ret & LIDAR_REG_STATUS_INVALID) {
>>                       *reg = 0;
>> -                     ret = 0;
>> +                     ret = -EIO;
>>                       break;
>>               }
>>
>>
>

Re: [PATCH] iio: lidar: return -EIO on invalid signal

[Jonathan Cameron]

On 01/11/15 00:47, Matt Ranostay wrote:
> Actually the INVALID status happens even it isn't out of range
> sometimes roughly once every second or two. This can be from an
> invalid second signal return path and etc..
> 
> So there are spurious zero readings from the triggered buffer, and
> warning messages in the kernel log.
Thanks for the clarification.  I've added a version of this response
to the patch description and applied to the fixes-togreg-post-rc1
branch I'm running at the moment as we have a few outstanding fixes
for stuff going in during the merge window that is opening very soon.

> 
> Thanks,
> 
> Matt
> 
> On Sat, Oct 31, 2015 at 2:29 AM, Jonathan Cameron <jic23@kernel.org> wrote:
>> On 25/10/15 23:07, Matt Ranostay wrote:
>>> Returning zero from the measurment function has the side effect of
>>> corrupting the triggered buffer readings, better to use -EIO than a
>>> zero measurement reading.
>> When you say 'corrupting' what do you mean?  As far as I can quickly see
>> it will give a spurious 0 distance when it really means a long distance.
>> Is that what you are referring to?
>>
>> Jonathan
>>>
>>> Signed-off-by: Matt Ranostay <mranostay@gmail.com>
>>> ---
>>>  drivers/iio/proximity/pulsedlight-lidar-lite-v2.c | 4 ++--
>>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
>>> index 961f9f99..359beac 100644
>>> --- a/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
>>> +++ b/drivers/iio/proximity/pulsedlight-lidar-lite-v2.c
>>> @@ -130,10 +130,10 @@ static int lidar_get_measurement(struct lidar_data *data, u16 *reg)
>>>               if (ret < 0)
>>>                       break;
>>>
>>> -             /* return 0 since laser is likely pointed out of range */
>>> +             /* return -EIO since laser is likely pointed out of range */
>>>               if (ret & LIDAR_REG_STATUS_INVALID) {
>>>                       *reg = 0;
>>> -                     ret = 0;
>>> +                     ret = -EIO;
>>>                       break;
>>>               }
>>>
>>>
>>
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