On 10/13/2010 3:58 PM, Laurent Pinchart wrote:
Hi Eino-Ville,
On Thursday 14 October 2010 00:03:33 Eino-Ville Talvala wrote:
Hi Laurent, linux-media,
We've been working on porting our OMAP3 ISP/mt9p031 Frankencamera framework
forward to the current kernel versions (currently, we're using the N900
ISP driver codebase, which is rather old by now). We'd been following
Sakari's omap3camera tree, but as is clear from this discussion, that's a
bad idea now.
(I'd love to just send out our mt9p031 driver code, but we still haven't
sorted out whether we're free to do so - since we're rewriting it a great
deal anyway, it hasn't been a priority to sort out.)
I've been handing off dev work on this to the next set of students on the
project, so I haven't been paying much attention to the mailing lists
recently, and I apologize if these questions have had clear answers
already.
Assuming one has a driver that works fine on the old v4l2_int_framework
back in .28-n900 kernel version - what is the best way forward to move it
to the 'current best option' framework, whatever that's currently
considered to be for the OMAP3 ISP? And for whatever option that is, is
there a document somewhere describing what needs to hooked up to what to
make that go, or is the best way to just look at the *-rx51 / et8ek8 code
in the right git repository?
First of all, you need to get the latest OMAP3 ISP driver sources.
The most recent OMAP3 ISP driver for the N900 can be found in the omap3isp-
rx51 git tree on gitorious.org (devel branch from
http://meego.gitorious.org/maemo-multimedia/omap3isp-rx51). This is the tree
used by MeeGo for the OMAP3 ISP camera driver. The driver has been ported to
the media controller framework, but the latest changes to the framework are
not present in that tree as they break the driver ABI and API. This should be
fixed in the future, but I can't give you any time estimate at the moment.
The most recent OMAP3 ISP driver and media controller framework can be found
in the pinchartl/media git tree on linuxtv.org (media-0004-omap3isp branch
from http://git.linuxtv.org/pinchartl/media.git). This is the tree used for
upstream submission of the media controller and OMAP3 ISP driver. The OMAP3
ISP driver implements the latest media controller API, but the tree doesn't
contain RX51 camera support.
As I assume you need RX51 camera support (arch/arm/mach-omap2/board-rx51-
camera.c, drivers/media/video/et8ek8.c, ...), the easiest solution is to go
for the gitorious.org tree. You will need to modify your code later when the
OMAP3 ISP driver will hit upstream, but the modifications will be very small
(mostly a matter of renaming constants or structure fields).
If you want to play with the latest media controller API, you could go for the
linuxtv.org tree and port the RX51 camera support from the gitorious.org tree.
That shouldn't be difficult, but time is unfortunately a scarce resource.
For userspace API documentation, run "make htmldocs" on the linuxtv.org tree
to generate HTML documentation, and navigate to
Documentation/DocBook/media/media_controller.html and
Documentation/DocBook/media/subdev.html.
Regarding the v4l2_int framework, your kernel drivers will need to be ported
to the V4L2 subdev framework and use pad-level operations. The et8ek8 driver
should be a good example. You can also have a look at the mt9t001 driver in
the media-mt9t001 branch from the linuxtv.org tree. The subdev pad-level
userspace API documentation will also help you understand the in-kernel API.
I hope this information will help you. Feel free to contact me if you have
further questions.
Thanks for the reply!
We're not terribly set on requiring rx51 support right - at least, I'm
assuming we couldn't just use the latest codebase for the ISP/et8ek8
drivers and get those to compile with the N900's release kernel, and we
don't want to ask end users to reflash their phone kernels to use our
programs and API.
Mostly, I just want to make sure that we try to ensure the fewest number
of substantial driver changes in the future, once we've gotten ourselves
up to the present. So if one of the two options you listed is the way
things will end up, I'd rather go with that and have a bit more work to
do if we need to support some other device that looks more like the rx51
in the future.
I gather the linux-tv branch is more like how things should end up
looking like, once the dust settles for a bit. So we port our driver
over to that, using the mt9t001 driver as an example of how everything
should be coded up, that should put us on a track of reasonable stability?
Also, is there a board file that has the needed sensor device
registration/power management/etc bits in that tree?
Thanks,
Eino-Ville
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