RE: OMAP 3530 camera ISP forks and new media framework

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On Thu, 7 Oct 2010, Hiremath, Vaibhav wrote:

> 
> > -----Original Message-----
> > From: linux-media-owner@xxxxxxxxxxxxxxx [mailto:linux-media-
> > owner@xxxxxxxxxxxxxxx] On Behalf Of Laurent Pinchart
> > Sent: Thursday, October 07, 2010 6:58 PM
> > To: Sakari Ailus
> > Cc: Bastian Hecht; Linux Media Mailing List
> > Subject: Re: OMAP 3530 camera ISP forks and new media framework
> > 
> > Hi Bastian,
> > 
> > On Thursday 07 October 2010 12:58:53 Sakari Ailus wrote:
> > > Bastian Hecht wrote:
> > >
> > > > I want to write a sensor driver for the mt9p031 (not mt9t031) camera
> > > > chip and start getting confused about the different kernel forks and

There is already an mt9t031 v4l2-subdev / soc-camera driver, so, if 
mt9t031 and mt9p031 are indeed similar enough, I think, the right way is 
to join efforts to port soc-camera over to the new "pad-level" API and 
re-use the driver.

Thanks
Guennadi

> > > > architectural changes that happen in V4L2.
> > > > A similar problem was discussed in this mailing list at
> > > > http://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg19084.html.
> > > >
> > > > Currently I don't know which branch to follow. Either
> > > > http://gitorious.org/omap3camera from Sakari Ailus or the branch
> > > > media-0004-omap3isp at http://git.linuxtv.org/pinchartl/media.git from
> > > > Laurent Pinchart. Both have an folder drivers/media/video/isp and are
> > > > written for the new media controller architecture if I am right.
> > >
> > > Take Laurent's branch it has all the current patches in it. My gitorious
> > > tree isn't updated anymore. (I just had forgotten to add a note, it's
> > > there now.)
> > >
> > > > I see in http://gitorious.org/omap3camera/camera-firmware that there
> > > > is already an empty placeholder for the mt9t031.
> > > > The README of the camera-firmware repository states: "makemodes.pl is
> > > > a perl script which converts sensor register lists from FIXME into C
> > > > code. dcc-pulautin is a Makefile (mostly) that converts sensor
> > > > register lists as C code into binaries understandable to sensor
> > > > drivers. The end result is a binary with sensor driver name, sensor
> > > > version and bin suffix, for example et8ek8-0002.bin."
> > > >
> > > > So I think the goal is to provide a script framework for camera
> > > > systems. You just script some register tables and it creates a binary
> > > > that can be read by a sensor driver made for that framework. If the a
> > > > camera bridge driver for your chip exists, you are done. Am I right?
> > > > Are drivers/media/video/et8ek8.c and
> > > > drivers/staging/dream/camera/mt9p012_* such drivers?
> > >
> > > et8ek8 and smia-sensor currently use the camera-firmware binaries. The
> > > long term goal is to move more things to the sensor driver itself.
> > > Register lists related to a set of sensor settings are not an ideal way
> > > to handle sensor related settings since they could be controlled the
> > > driver instead.
> > 
> > To be compatible with the OMAP3 ISP driver, sensor drivers need to provide
> > a
> > v4l2_subdev interface and implement the pad-level operations (see the
> > media-0003-subdev-pad branch in the repository).
> > 
> > I've written such a driver for the MT9T001. I've pushed it to the media-
> > mt9t001 branch on http://git.linuxtv.org/pinchartl/media.git. Please note
> > that
> > the driver is based on a previous version of the subdev pad-level
> > operations
> > API, so it won't compile out of the box.
> > 
> 
> 
> Just to add ontop of this, you can find couple of more sensor (MT9V113 & MT9T111) sub-dev driver at 
> 
> http://arago-project.org/git/people/vaibhav/ti-psp-omap-video.git?p=people/vaibhav/ti-psp-omap-video.git;a=shortlog;h=refs/heads/omap3cam-mc-devel
> 
> 
> Also I have already ported these sensor drivers to latest sub-dev pad level operations but have not tested and pushed to the Repository which I will do by this weekend.
> 
> Thanks,
> Vaibhav
> 
> > As Sakari stated, the camera-firmware system shouldn't be used by new
> > drivers.
> > The driver should instead compute the register values directly from the
> > information supplied by userspace (through the v4l2_subdev API) such as
> > the
> > frame size and the crop rectangle. Binary lists of register address/value
> > pairs are definitely not the way to go.
> > 
> > > > So do you think it is the right way to go to use your ISP driver,
> > > > adapt drivers/staging/dream/camera/mt9p012_* to suit my mt9p031 and
> > > > write a register list and create a camera firmware for that sensor
> > > > driver with makemodes?
> > >
> > > I would go with drivers/media/video/et8ek8.c in Laurent's tree instead
> > > if you want to write a sensor driver to be used with the OMAP 3 ISP
> > > driver. Register lists are not that nice but the v4l2_subdev interface
> > > in that one is one of the good parts you get with that.
> > 
> > Start with the MT9T001 driver, that will be easier.
> > 
> > > I'd also advice against using camera-firmware if you don't necessarily
> > > need that kind of functionality.
> > 
> > I'd very strongly advice against it as well. Try to forget it even exists,
> > it
> > was a development mistake :-)
> > 
> > > > I am still quite confused... if I get something wrong, please give me
> > > > some hints.
> > >
> > > I hope this helped. :-)
> > >
> > > If you have any further questions feel free to ask.
> > 
> > Ditto :-)
> > 
> > --
> > Regards,
> > 
> > Laurent Pinchart

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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