> What do you think about 'Bugfix for missing Lux returning in dark
> environment' ?
That covers the key point, so fine.
> Jonathan Cameron wrote:
>> Looks good to me. (perhaps a bit more detail in the commit
>> message of the patch?)
>>
>> Acked-by: Jonathan Cameron <jic23@xxxxxxxxx>
>>
>>> Jonathan Cameron wrote:
>>>
>>>> Michele De Candia (VT) wrote:
>>>>
>>>>
>>>>> Hi all,
>>>>>
>>>>> I've tested TSL2550 driver and I've found a bug: when light is off,
>>>>> returned value from tsl2550_calculate_lux function is -1 when it
>>>>> should
>>>>> be 0 (sensor correctly read that light was off).
>>>>>
>>>>> I think the bug is that a zero c0 value (approximated value of ch0) is
>>>>> misinterpreted as an error.
>>>>> I'm attaching you a patch that fixes the bug.
>>>>>
>>>>> Regards,
>>>>> Michele Jr De Candia
>>>>>
>>>> Sounds reasonable, but I think a stray line got away in your patch
>>>> (see below)
>>>> Not to mention, if the c1 <= c0 check is still valid, should you not
>>>> also
>>>> confirm that c1 == 0 as well? Perhaps reverse the ordering?
>>>>
>>> That's right. A new patch can be found in attachment.
>>>
>>>> if (c1 <= c0)
>>>> if(c0) {
>>>> r = c1* 128 / c0;
>>>> lux = ((c0 - c1) * ratio_lut[r]) / 256;
>>>> } else
>>>> lux = 0;
>>>> else
>>>> return -1;
>>>>
>>>> Signed-off-by: Michele Jr De Candia <michele.decandia@xxxxxxxxxxxxx>
>>>>
>>>> diff --git a/drivers/i2c/chips/tsl2550.c b/drivers/i2c/chips/tsl2550.c
>>>> index 1a9cc13..6bad072 100644
>>>> --- a/drivers/i2c/chips/tsl2550.c
>>>> +++ b/drivers/i2c/chips/tsl2550.c
>>>> @@ -189,10 +189,16 @@ static int tsl2550_calculate_lux(u8 ch0, u8 ch1)
>>>> u8 r = 128;
>>>>
>>>> /* Avoid division by 0 and count 1 cannot be greater than count
>>>> 0 */
>>>> - if (c0 && (c1 <= c0))
>>>> - r = c1 * 128 / c0;
>>>> - else
>>>> - return -1;
>>>> + if (c0) {
>>>> + if (c1 <= c0)
>>>> + r = c1 * 128 / c0;
>>>> + else
>>>> + return -1;
>>>> + + /* Calculate LUX */
>>>> + lux = ((c0 - c1) * ratio_lut[r]) / 256;
>>>> + }
>>>> + else lux = 0;
>>>>
>>>>
>>>> This last line should have been removed I think?
>>>> /* Calculate LUX */
>>>> lux = ((c0 - c1) * ratio_lut[r]) / 256;
>>>>
>>>> ---
>>>> Jonathan Cameron
>>>>
>>>>
>>> Than
>>>
>>
>>
>
>
--
To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
