Re: [PATCH] media: staging: drop omap4iss

[Andreas Kemnade <andreas@kemnade.info>]

Am Wed, 20 Nov 2024 10:39:38 +0200
schrieb Laurent Pinchart <laurent.pinchart@ideasonboard.com>:

> Hi Andreas,
> 
> On Wed, Nov 20, 2024 at 08:54:06AM +0100, Andreas Kemnade wrote:
> > Am Tue, 19 Nov 2024 09:02:22 +0200 schrieb Laurent Pinchart:  
> > > On Mon, Nov 18, 2024 at 08:00:25PM +0100, Andreas Kemnade wrote:  
> > > > Am Mon, 2 Sep 2024 10:42:31 +0200 schrieb Hans Verkuil :
> > > >     
> > > > > The omap4 camera driver has seen no progress since forever, and
> > > > > now OMAP4 support has also been dropped from u-boot (1). So it is
> > > > > time to retire this driver.    
> > > > 
> > > > Argumenting with OMAP4 support in U-Boot is silly. That indicates that
> > > > there is no movement in keeping u-boot uptodate. Bootloader
> > > > development/updating is more risky especially if not done by the vendor,
> > > > good chances to brick something. And the bootloader might need
> > > > signing. So that argument is done nothing.
> > > > 
> > > > Better arguments would be to check if someone has something cooking and
> > > > feels not comfortable yet to climb Mount Upstream.
> > > > 
> > > > A good place to ask would be the omap platform
> > > > list: linux-omap@vger.kernel.org
> > > > 
> > > > I get still devicetrees for omap4 devices to review. So there is some
> > > > activity with omap4. If you look at postmarketOS you see also some
> > > > activity.
> > > > 
> > > > And also someone ported the driver to devicetree support:
> > > > https://github.com/iridia-ulb/meta-builderbot/blob/master/recipes-kernel/linux/linux-stable-4.16/0008-omap4iss-Fix-multiple-bugs-and-use-device-tree.patch
> > > > 
> > > > So the situation is not that simple. I am still evaluating it because I
> > > > myself have a device with omap4 and camera.    
> > > 
> > > Have you tested the camera recently ? The omap4iss driver has been
> > > unmaintained in mainline for a very, very long time, and I would be
> > > surprised if it worked.  
> > 
> > No, I have not tested it. I only have a bitrot out of tree driver for my
> > camera which was probably never used with omap. Vendor system seems to
> > handle camera via the m3 processor in a closed-source firmware blob. So
> > what is the overall picture:
> > 
> > Which omap4 devices have cameras? What is the status of the sensor
> > driver? Known working/Mainline/Out-of-tree/none? Datasheet for
> > sensor available?
> > The question is whether omap4iss can be tested together with a
> > known-working camera sensor driver. That would make things a lot easier.
> >
> > BT200 has a camera without mainline sensor driver.
> > Droid4 has also a camera. What is the status of the sensor driver?
> > What about the samsung-espresso tablets? And the xyboards?
> > 
> > Pandaboard camera module? If have a pandaboard I use for reference, but
> > no camera there.  
> 
> I used to work on it using a Pandaboard and an MT9P031 camera module,
> from Leopard Imaging if I recall correctly.
>
Hmm, that would require also soldering the connector and it seems like
no standard thing, so I would need to create an adaptor. At least I do
not find anything on ebay which looks like it can be attached to the
Pandaboard.

> > > If someone is interested in taking over maintainership and improving the
> > > driver to get it out of drivers/staging/ to drivers/media/, the removal
> > > can certainly be reverted. drivers/staging/ is not a place where drivers
> > > are left to bitrot, it's meant for active development of code not fully
> > > ready for mainline yet.  
> > 
> > I guess the way to start is to revert the remove and then update the
> > above-mentioned devicetree support patch. I have no feeling how complex
> > that whole task would be.  
> 
> That would be a first step, yes. After that, completing resizer support
> will be a good task candidate, followed by exposing the ISP parameters
> to userspace, and adding support for it to libcamera.
> 
Well, I guess before adding the resizer stuff, I want to see a picture
influenced by what is in front of the camera of a device I really care
about (!= pandaboard) and then adjusting things to the point where
format configurations are solved. At some point more could also jump
in to screw at sensor chip drivers.

Regards,
Andreas