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SubjectRe: [PATCH 2/4] staging: atomisp: simplify if statement in atomisp_get_sensor_fps()


Am 20.03.2017 13:51, schrieb DaeSeok Youn:
> 2017-03-20 21:04 GMT+09:00 walter harms <wharms@bfs.de>:
>>
>>
>> Am 20.03.2017 11:59, schrieb Daeseok Youn:
>>> If v4l2_subdev_call() gets the global frame interval values,
>>> it returned 0 and it could be checked whether numerator is zero or not.
>>>
>>> If the numerator is not zero, the fps could be calculated in this function.
>>> If not, it just returns 0.
>>>
>>> Signed-off-by: Daeseok Youn <daeseok.youn@gmail.com>
>>> ---
>>> .../media/atomisp/pci/atomisp2/atomisp_cmd.c | 22 ++++++++++------------
>>> 1 file changed, 10 insertions(+), 12 deletions(-)
>>>
>>> diff --git a/drivers/staging/media/atomisp/pci/atomisp2/atomisp_cmd.c b/drivers/staging/media/atomisp/pci/atomisp2/atomisp_cmd.c
>>> index 8bdb224..6bdd19e 100644
>>> --- a/drivers/staging/media/atomisp/pci/atomisp2/atomisp_cmd.c
>>> +++ b/drivers/staging/media/atomisp/pci/atomisp2/atomisp_cmd.c
>>> @@ -153,20 +153,18 @@ struct atomisp_acc_pipe *atomisp_to_acc_pipe(struct video_device *dev)
>>>
>>> static unsigned short atomisp_get_sensor_fps(struct atomisp_sub_device *asd)
>>> {
>>> - struct v4l2_subdev_frame_interval frame_interval;
>>> + struct v4l2_subdev_frame_interval fi;
>>> struct atomisp_device *isp = asd->isp;
>>> - unsigned short fps;
>>>
>>> - if (v4l2_subdev_call(isp->inputs[asd->input_curr].camera,
>>> - video, g_frame_interval, &frame_interval)) {
>>> - fps = 0;
>>> - } else {
>>> - if (frame_interval.interval.numerator)
>>> - fps = frame_interval.interval.denominator /
>>> - frame_interval.interval.numerator;
>>> - else
>>> - fps = 0;
>>> - }
>>> + unsigned short fps = 0;
>>> + int ret;
>>> +
>>> + ret = v4l2_subdev_call(isp->inputs[asd->input_curr].camera,
>>> + video, g_frame_interval, &fi);
>>> +
>>> + if (!ret && fi.interval.numerator)
>>> + fps = fi.interval.denominator / fi.interval.numerator;
>>> +
>>> return fps;
>>> }
>>
>>
>>
>> do you need to check ret at all ? if an error occurs can fi.interval.numerator
>> be something else than 0 ?
> the return value from the v4l2_subdev_call() function is zero when it
> is done without any error. and also I checked
> the ret value whether is 0 or not. if the ret is 0 then the value of
> numerator should be checked to avoid for dividing by 0.
>>
>> if ret is an ERRNO it would be wise to return ret not fps, but this may require
>> changes at other places also.
> hmm.., yes, you are right. but I think it is ok because the
> atomisp_get_sensor_fps() function is needed to get fps value.
> (originally, zero or calculated fps value was returned.)

maybe its better to divide this in:
if (ret)
return 0; // error case

return (fi.interval.numerator>0)?fi.interval.denominator / fi.interval.numerator:0;

So there is a chance that someone will a) understand and b) fix the error return.

re,
wh

>
>>
>> re,
>> wh
>>
>>>
>

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