Re: [PATCH] media: Add camera controls for the ov5642 driver

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hello Sakari,

2011/9/6 Sakari Ailus <sakari.ailus@xxxxxx>:
> On Tue, Sep 06, 2011 at 09:35:24AM +0000, Bastian Hecht wrote:
>> Hello Sakari,
>>
>> 2011/9/6 Sakari Ailus <sakari.ailus@xxxxxx>:
>> > On Tue, Sep 06, 2011 at 09:01:15AM +0000, Bastian Hecht wrote:
>> >> 2011/9/6 Sakari Ailus <sakari.ailus@xxxxxx>:
>> >> > On Tue, Sep 06, 2011 at 07:56:40AM +0000, Bastian Hecht wrote:
>> >> >> Hello Sakari!
>> >> >
>> >> > Hi Bastian,
>> >> >
>> >> >> 2011/9/6 Sakari Ailus <sakari.ailus@xxxxxx>:
>> >> >> > Hi Bastian,
>> >> >> >
>> >> >> > On Mon, Sep 05, 2011 at 09:32:55AM +0000, Bastian Hecht wrote:
>> >> >> >> 2011/9/1 Sakari Ailus <sakari.ailus@xxxxxx>:
>> >> >> >> > On Thu, Sep 01, 2011 at 11:14:08AM +0200, Sylwester Nawrocki wrote:
>> >> >> >> >> Hi Sakari,
>> >> >> >> >>
>> >> >> >> >> On 09/01/2011 10:47 AM, Sakari Ailus wrote:
>> >> >> >> >> > On Thu, Sep 01, 2011 at 09:15:20AM +0200, Guennadi Liakhovetski wrote:
>> >> >> >> >> >> On Thu, 1 Sep 2011, Sakari Ailus wrote:
>> >> >> >> >> >>
>> >> >> >> >> >>> On Wed, Aug 31, 2011 at 03:27:49PM +0000, Bastian Hecht wrote:
>> >> >> >> >> >>>> 2011/8/28 Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>:
>> >> >> >> >> >>> [clip]
>> >> >> >> >> >>>>> If I'm not mistaken V4L2_CID_PRIVATE_BASE is deprecated.
>> >> >> >> >> >>>>
>> >> >> >> >> >>>> I checked at http://v4l2spec.bytesex.org/spec/x542.htm, googled
>> >> >> >> >> >>>> "V4L2_CID_PRIVATE_BASE deprecated" and read
>> >> >> >> >> >>>> Documentation/feature-removal-schedule.txt. I couldn't find anything.
>> >> >> >> >> >>>
>> >> >> >> >> >>> Hmm. Did you happen to check when that has been written? :)
>> >> >> >> >> >>>
>> >> >> >> >> >>> Please use this one instead:
>> >> >> >> >> >>>
>> >> >> >> >> >>> <URL:http://hverkuil.home.xs4all.nl/spec/media.html>
>> >> >> >> >> >>
>> >> >> >> >> >> "Drivers can also implement their own custom controls using
>> >> >> >> >> >> V4L2_CID_PRIVATE_BASE and higher values."
>> >> >> >> >> >>
>> >> >> >> >> >> Which specific location describes V4L2_CID_PRIVATE_BASE differently there?
>> >> >> >> >> >
>> >> >> >> >> > That was a general comment, not related to the private base. There's no
>> >> >> >> >> > use for a three-year-old spec as a reference!
>> >> >> >> >> >
>> >> >> >> >> > The control framework does not support private controls, for example. The
>> >> >> >> >> > controls should be put to their own class in videodev2.h nowadays, that's my
>> >> >> >> >> > understanding. Cc Hans.
>> >> >> >> >>
>> >> >> >> >> Is this really the case that we close the door for private controls in
>> >> >> >> >> the mainline kernel ? Or am I misunderstanding something ?
>> >> >> >> >> How about v4l2_ctrl_new_custom() ?
>> >> >> >> >>
>> >> >> >> >> What if there are controls applicable to single driver only ?
>> >> >> >> >> Do we really want to have plenty of such in videodev2.h ?
>> >> >> >> >
>> >> >> >> > We have some of those already in videodev2.h. I'm not certain if I'm happy
>> >> >> >> > with this myself, considering e.g. that we could get a few truckloads of
>> >> >> >> > only camera lens hardware specific controls in the near future.
>> >> >> >>
>> >> >> >> So in my case (as these are controls that might be used by others too)
>> >> >> >> I should add something like
>> >> >> >>
>> >> >> >> #define V4L2_CID_BLUE_SATURATION              (V4L2_CID_CAMERA_CLASS_BASE+19)
>> >> >> >> #define V4L2_CID_RED_SATURATION               (V4L2_CID_CAMERA_CLASS_BASE+20)
>> >> >> >
>> >> >> > What do these two controls do? Do they control gain or something else?
>> >> >>
>> >> >> Hmm. Maybe I named them a bit unsharp. It is the U Saturation and V
>> >> >> Saturation. To me it looks like turning up the saturation in HSV
>> >> >> space, but only for either the blue or the red channel. This would
>> >> >> correspond to V4L2_CID_{RED,BLUE}_BALANCE when I read the docs. They
>> >> >> say it is "{Red,Blue} chroma balance".
>> >> >>
>> >> >> I have other controls for that I used V4L2_CID_{RED,BLUE}_BALANCE.
>> >> >> These are gains. So in fact I should swap them in my code and the
>> >> >> remaining question is, how to name the red and blue gain controls.
>> >> >
>> >> > I think Laurent had a similar issue in his Aptina sensor driver. In my
>> >> > opinion we need a class for low level controls such as the gain ones. Do I
>> >> > understand correctly they control the red and blue pixel gain in the sensor
>> >> > pixel matrix? Do you also have gain controls for the two greens?
>> >>
>> >> Yes, I assume that this is done there. Either in the analog circuit by
>> >> decreasing the preload or digitally then. Don't know exactly. There
>> >> are registers for the green pixels as well. As I used the
>> >> V4L2_CID_{RED,BLUE}_BALANCE controls and there was no
>> >> V4L2_CID_GREEN_BALANCE, I just skipped green as one can
>> >> increase/decrease the global gain and get an arbitrary mix as well.
>> >>
>> >> So for these gain settings we should add these?
>> >> V4L2_CID_RED_GAIN
>> >> V4L2_CID_BLUE_GAIN
>> >> V4L2_CID_GREEN_GAIN
>> >
>> > Do you have two or just one green gains? In all sensors I've seen there are
>> > two.
>>
>> No, here is only one.
>
> It is a raw bayer sensor, isn't it?
>
>> > I think I could send an RFC on this to the list and cc you and Laurent.
>>
>> Ok fine, thanks! But hmmm - what do I do with my driver in the
>> meantime actually? Stall the upstream process or remove my controls
>> temporarily - or is there a better way?
>
> It is also possible to expose these controls just for this sensor, but I
> would wait a little bit if that's okay for you. Your sensor driver isn't the
> only one depending on these new controls --- Laurent also has one.
>
> I don't think this should take too long, but I can't promise that. :-)
>
> If you want the driver to mainline fast, then you could also submit it
> without these controls implemented, and implement them in another patch when
> the controls have been standardised.

Ok, thanks for the info. I'll try it this way: I'll post an
[PATCH/RFC] with the final version except the right control names for
gain and chroma balance. So when this rfc gets through, I can simply
change names and am done.

>> >> >> >> #define V4L2_CID_GRAY_SCALE_IMAGE             (V4L2_CID_CAMERA_CLASS_BASE+21)
>> >> >> >
>> >> >> > V4L2_CID_COLOR_KILLER looks like something which would fit for the purpose.
>> >> >>
>> >> >> Oh great! So I just take this.
>> >> >>
>> >> >> >> #define V4L2_CID_SOLARIZE_EFFECT              (V4L2_CID_CAMERA_CLASS_BASE+22)
>> >> >> >
>> >> >> > Sounds interesting for a sensor. I wonder if this would fall under a menu
>> >> >> > control, V4L2_CID_COLORFX.
>> >> >>
>> >> >> When I read the the possible enums for V4L2_CID_COLORFX, it indeed
>> >> >> sounds very much like my solarize effect should be added there too. I
>> >> >> found V4L2_COLORFX_BW there, too. Isn't that a duplicate of the color
>> >> >> killer control then?
>> >> >
>> >> > In my opinion V4L2_CID_COLORFX should never be implemented in drivers for
>> >> > which the hardware doesn't implement these effects in a non-parametrisable
>> >> > way. This control was originally added for the OMAP 3 ISP driver but the
>> >> > driver never implemented it.
>> >>
>> >> Your triple negation (never, doesn't, non-) is quite tricky xD
>> >> If I get it right, you say that one should not use V4L2_CID_COLORFX
>> >> for hardware with parametrisable effects.
>> >
>> > Yes. I could have written that in a more clear way. ;-)
>>
>> After starring dazzled for 2 minutes on it, I realized at some point
>> that formal logic is your friend ;)
>>
>> >> My BW and Solarize effects are non-parametrisable and they can be
>> >> turned on together (which makes not so much sense though - but these
>> >> fun-effects like "solarize" aren't here to make sense, I guess :-) ).
>> >
>> > Good.
>> >
>> > The OMAP 3 ISP actually provides a way to set gamma tables, any effects
>> > implemented using them are more or less use case specific. There are also
>> > other uses for those same gamma tables, making a driver implementation for
>> > effects using them non-functional in practice.
>>
>> Ok I see. Luckily (for me) in my sensor it is binary on/off only.
>>
>> >> > I think you have a valid case using this control. I think the main
>> >> > difference between the two is that V4L2_COLORFX_BW is something that you
>> >> > can't use with other effects while V4L2_CID_COLOR_KILLER can be used with
>> >> > any of the effects.
>> >>
>> >> > Based on your original proposal the black/white should stay as a separate
>> >> > control but the solarise should be configurable through V4L2_CID_COLORFX
>> >> > menu control. So it boils down to the question whether you can use them at
>> >> > the same time.
>> >>
>> >> I can - so it is still working to enable V4L2_COLORFX_BW and
>> >> V4L2_CID_COLORFX with a new enum value, right? Is that the way to go
>> >> now?
>> >
>> > That's my opinion, yes.
>>
>> So I will post an additional patch for videodev2.h with
>> enum v4l2_colorfx {
>>         ...
>>       V4L2_COLORFX_SOLARIZE = 10,
>> };
>
> That's correct. I think the COLORFX hasn't been very well documented so far,
> but it should be. I don't think many know what the solarize effect would do.
> :-) I think the patch should also add that. The user control documentation
> may be found in Documentation/DocBook/media/v4l/controls.xml .
>
> Cheers,

In fact, I had no idea as well, but wikipedia teached me :)
So I will prepare a documentation patch as well.
http://en.wikipedia.org/wiki/Solarisation

> --
> Sakari Ailus
> e-mail: sakari.ailus@xxxxxx     jabber/XMPP/Gmail: sailus@xxxxxxxxxxxxxx
>

best,

 Bastian
--
To unsubscribe from this list: send the line "unsubscribe linux-media" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html


[Index of Archives]     [Linux Input]     [Video for Linux]     [Gstreamer Embedded]     [Mplayer Users]     [Linux USB Devel]     [Linux Audio Users]     [Linux Kernel]     [Linux SCSI]     [Yosemite Backpacking]
  Powered by Linux