Guennadi Liakhovetski wrote:
On Thu, 18 Jun 2009, Valentin Longchamp wrote:
Hi Guennadi,
I am trying to follow your developments at porting soc-camera to v4l2-subdev.
However, even if I understand quite correctly soc-camera, it is quite
difficult for me to get all the subtleties in your work.
That's why I am asking you for a little help: when do you think would be the
best timing for me to add the mt9t031 camera support for mx31moboard within
your current process ?
You can do this now, based either on the v4l tree, or wait for Linus to
pull it - a pull request has been sent ba Mauro yesterday, looks like
Linus hasn't pulled yet.
The way you add your platform is going to change, and the pull, that I'm
referring to above makes it possible for both "old style" and "new style"
board camera data to work. Of course, it would be best for you to
implement the "new style" platform data. You can do this by either looking
at my patches, which I've posted to the lists earlier, and which are also
included in my patch stack, which I announced yesterday. Or you can wait a
bit until I update my pcm037 patch (going to do this now) and post it to
arm-kernel. I'll (try not to forget to) add you to cc, that should be
quite easy to follow for you.
I guess it should not be too difficult, I had done it before, and I can base
myself on what you have done for pcm037:
http://download.open-technology.de/soc-camera/20090617/0025-pcm037-add-MT9T031-camera-support.patch
Yes, use this or wait a bit for an updated version.
OK, thanks a lot. Since I am busy at other things at the moment, I am
going to wait for you updated version and that things are stabilized a
little bit with the 31-rc1. And I will use the "new style" platform data.
Now I have a second question. On our robot, we physically have two cameras
(one looking to the front and one looking at a mirror) connected to the i.MX31
physical bus. We have one signal that allows us to control the multiplexer for
the bus lines (video signals and I2C) through a GPIO. This now works with a
single camera declared in software and choices to the multiplexer done when no
image transfer is happening ( /dev/video is not open). What do you think
should be the correct way of dealing with these two cameras with the current
driver implementation (should I continue to declare only one camera in the
software) ?
And do you think it could be possible to "hot-switch" from one camera to the
other ? My colleagues ask about it, I tell them that from my point of view
this seems not possible without changing the drivers, and even the drivers
would have to be changed quite heavily and it is not trivial.
Do the cameras use different i2c addresses? If they use the same address I
don't think you'd be able to register them simultaneously. If they do use
different addresses, you can register both of them and use platform
.power() callback to switch between them using your multiplexer. See
arch/sh/boards/mach-migor/setup.c for an example. There was also a
proposal to use switching input to select a data source, but this is
currently unsupported by soc-camera.
The sensor chips both are mt9t031 so they have the same i2c address (I
have looked at the datasheet, and I don't think this can be changed). So
I cannot use them both at the same time.
Now you talk about the .power() callback, I could use it so that the
multiplexer is managed by it, using a similar mechanism as in
mach-migor. If this could allow me one different /dev/video nod for each
camera (that of course cannot be used at the same time), it would
simplify a lot of things for my users. I will give it a try (hoping that
this also works at driver registering ... we will see).
Thanks for your answers.
Val
--
Valentin Longchamp, PhD Student, EPFL-STI-LSRO1
valentin.longchamp@xxxxxxx, Phone: +41216937827
http://people.epfl.ch/valentin.longchamp
MEA3485, Station 9, CH-1015 Lausanne
--
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
