[libcamera-devel] [RFC] media: Auto exposure/gain support for atomisp / libcamera integration ?

[Hans de Goede]

Hi,

On 11/18/21 11:50, Laurent Pinchart wrote:
> Hi Umang,
> 
> On Thu, Nov 18, 2021 at 03:43:53PM +0530, Umang Jain wrote:
>> On 11/7/21 11:20 PM, Hans de Goede wrote:
>>> Hi All,
>>>
>>> Now that we have the atomisp2 driver running on some devices like
>>> the Asus T101HA; and with the exposure + gain controls for the ov2680
>>> sensor found on that laptop fixed:
>>>
>>> https://lore.kernel.org/linux-media/20211107171549.267583-1-hdegoede@redhat.com/
>>>
>>> I believe we need to start thinking about various userspace API
>>> concerns. Thanks to Mauro's great work on various V4L2 API things
>>> are starting to work (somewhat) with regular V4L2 apps, but we really
>>> also need some processing / 3A stuff to make the cameras really
>>> usable.
>>>
>>> The most important thing needed is automatic exposure + gain control,
>>> ATM this relies on a custom ATOMISP ioctl, but I believe that we can
>>> just export the controls as regular v4l2 controls on the sensor subdev,
>>> at least for the ov2680 the exposure is already exported this way
>>> but it is read-only. Does anyone see any problems with just making
>>> these normal v4l2 controls on the sensor subdev ?
>>>
>>> We can then simulate the custom ATOMISP ioctl through the subdevs,
>>> or we can just remove it alltogether.
>>>
>>> Once we have the controls available this way I think we should write
>>> a libcamera plugin, which like the older versions of the Rasberry Pi
>>> plugin (if I've understood things correctly) won't use the MC framework
>>> for now. I believe we first need to understand the atomisp code better
>>> before we add MC support (*). But I still believe that an (experimental)
>>> plugin would be good, both to get something usable so that we can get
>>> more testers / more people interested in contributing.
>>
>> I am trying to understand what 'plugin' here means? Is it a wrapper 
>> pertaining to use libcamera (fined tuned for atomisp) that apps can use?
> 
> I think it means pipeline handler (and IPA module).

Right, I'm still getting used to the libcamera naming of things :)

Regards,

Hans