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[PATCH v3 16/28] staging: iio: tsl2583: updated code comment to match what the code does

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  [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to match what the code does Brian Masney <masneyb@onstation.org> - 2016-11-10 10:40 +0100
    Re: [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to  match what the code does Jonathan Cameron <jic23@kernel.org> - 2016-11-12 17:40 +0100
      Re: [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to  match what the code does Brian Masney <masneyb@onstation.org> - 2016-11-12 18:00 +0100
        Re: [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to  match what the code does Jonathan Cameron <jic23@kernel.org> - 2016-11-12 18:20 +0100

#1518797 — [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to match what the code does

If channel 0 does not have any data, then the code sets the lux to zero.
The corresponding comment says that the last value is returned. This
updates the comment to correctly reflect what the code does.

Signed-off-by: Brian Masney <masneyb@onstation.org>
---
 drivers/staging/iio/light/tsl2583.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/staging/iio/light/tsl2583.c b/drivers/staging/iio/light/tsl2583.c
index 52a39a6..390ff8b 100644
--- a/drivers/staging/iio/light/tsl2583.c
+++ b/drivers/staging/iio/light/tsl2583.c
@@ -221,7 +221,7 @@ static int tsl2583_get_lux(struct iio_dev *indio_dev)
 		goto return_max;
 
 	if (!ch0) {
-		/* have no data, so return LAST VALUE */
+		/* have no data, so return 0 */
 		ret = 0;
 		chip->als_cur_info.lux = 0;
 		goto done;
-- 
2.7.4

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#1520269 — Re: [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to match what the code does

On 10/11/16 09:25, Brian Masney wrote:
> If channel 0 does not have any data, then the code sets the lux to zero.
> The corresponding comment says that the last value is returned. This
> updates the comment to correctly reflect what the code does.
> 
> Signed-off-by: Brian Masney <masneyb@onstation.org>
Better perhaps to just return an error, -EAGAIN perhaps?
I'm not sure why it would not give a value.
> ---
>  drivers/staging/iio/light/tsl2583.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/staging/iio/light/tsl2583.c b/drivers/staging/iio/light/tsl2583.c
> index 52a39a6..390ff8b 100644
> --- a/drivers/staging/iio/light/tsl2583.c
> +++ b/drivers/staging/iio/light/tsl2583.c
> @@ -221,7 +221,7 @@ static int tsl2583_get_lux(struct iio_dev *indio_dev)
>  		goto return_max;
>  
>  	if (!ch0) {
> -		/* have no data, so return LAST VALUE */
> +		/* have no data, so return 0 */
>  		ret = 0;
>  		chip->als_cur_info.lux = 0;
>  		goto done;
> 

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#1520278 — Re: [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to match what the code does

On Sat, Nov 12, 2016 at 04:36:37PM +0000, Jonathan Cameron wrote:
> On 10/11/16 09:25, Brian Masney wrote:
> > If channel 0 does not have any data, then the code sets the lux to zero.
> > The corresponding comment says that the last value is returned. This
> > updates the comment to correctly reflect what the code does.
> > 
> > Signed-off-by: Brian Masney <masneyb@onstation.org>
> Better perhaps to just return an error, -EAGAIN perhaps?
> I'm not sure why it would not give a value.

This check is to avoid a division by zero. Here is the relevant code
that wasn't shown in the diff:

	if (!ch0) {
		/* have no data, so return 0 */
		ret = 0;
		chip->als_cur_info.lux = 0;
		goto done;
	}

	/* calculate ratio */
	ratio = (ch1 << 15) / ch0;

Channel 0 is sensitive to both infrared and visible light. In total
darkness, the sensor should return 0. Correct me if I am wrong, but
I believe that returning 0 here is more correct than -EAGAIN.

Brian

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#1520287 — Re: [PATCH v3 16/28] staging: iio: tsl2583: updated code comment to match what the code does

On 12/11/16 16:59, Brian Masney wrote:
> On Sat, Nov 12, 2016 at 04:36:37PM +0000, Jonathan Cameron wrote:
>> On 10/11/16 09:25, Brian Masney wrote:
>>> If channel 0 does not have any data, then the code sets the lux to zero.
>>> The corresponding comment says that the last value is returned. This
>>> updates the comment to correctly reflect what the code does.
>>>
>>> Signed-off-by: Brian Masney <masneyb@onstation.org>
>> Better perhaps to just return an error, -EAGAIN perhaps?
>> I'm not sure why it would not give a value.
> 
> This check is to avoid a division by zero. Here is the relevant code
> that wasn't shown in the diff:
> 
> 	if (!ch0) {
> 		/* have no data, so return 0 */
> 		ret = 0;
> 		chip->als_cur_info.lux = 0;
> 		goto done;
> 	}
> 
> 	/* calculate ratio */
> 	ratio = (ch1 << 15) / ch0;
> 
> Channel 0 is sensitive to both infrared and visible light. In total
> darkness, the sensor should return 0. Correct me if I am wrong, but
> I believe that returning 0 here is more correct than -EAGAIN.
> 
> Brian
> 
Fair enough I hadn't understood that.  Maybe expand the comment
to cover that?

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