Re: [PATCH v7 1/2] [media] atmel-isc: add the Image Sensor Controller code

[Hans Verkuil <hverkuil@xs4all.nl>]

On 08/02/2016 08:20 AM, Wu, Songjun wrote:
>>> +static unsigned int sensor_preferred = 1;
>>> +module_param(sensor_preferred, uint, S_IRUGO|S_IWUSR);
>>> +MODULE_PARM_DESC(sensor_preferred,
>>> +		 "Sensor is preferred to output the specified format (1-on 0-off) default 1");
>>
>> I have no idea what this means. Can you elaborate? Why would you want to set this to 0?
>>
> ISC can convert the raw format to the other format, e.g. YUYV.
> If we want to output YUYV format, there are two choices, one is the 
> sensor output YUYV format, ISC bypass the data to the memory, the other 
> is the sensor output raw format, ISC convert raw format to YUYV.
> 
> So I provide a module parameter to user to select.
> I prefer to select the sensor to output the specified format, then I set 
> this parameter to '1', not '0'.

Does this only apply to YUYV?

The reason I am hesitant about this option is that I am not convinced you need
it. The default (sensor preferred) makes sense and that's what other drivers
do as well. Unless you know of a real use-case where you want to set this to 0,
I would just drop this option.

If there *is* a real use-case, then split off adding this module option into a
separate patch so we can discuss it more without blocking getting this driver
into mainline. I don't like the way this is done here.

Regards,

	Hans