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

[Brian Masney]

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@xxxxxxxxxxxxx>
> 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