Re: [PATCH] staging: ion: remove from the tree

[Greg Kroah-Hartman]

On Thu, Aug 27, 2020 at 10:31:41PM +0530, Amit Pundir wrote:
> On Thu, 27 Aug 2020 at 21:34, Greg Kroah-Hartman
> <gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
> >
> > On Thu, Aug 27, 2020 at 09:31:27AM -0400, Laura Abbott wrote:
> > > On 8/27/20 8:36 AM, Greg Kroah-Hartman wrote:
> > > > The ION android code has long been marked to be removed, now that we
> > > > dma-buf support merged into the real part of the kernel.
> > > >
> > > > It was thought that we could wait to remove the ion kernel at a later
> > > > time, but as the out-of-tree Android fork of the ion code has diverged
> > > > quite a bit, and any Android device using the ion interface uses that
> > > > forked version and not this in-tree version, the in-tree copy of the
> > > > code is abandonded and not used by anyone.
> > > >
> > > > Combine this abandoned codebase with the need to make changes to it in
> > > > order to keep the kernel building properly, which then causes merge
> > > > issues when merging those changes into the out-of-tree Android code, and
> > > > you end up with two different groups of people (the in-kernel-tree
> > > > developers, and the Android kernel developers) who are both annoyed at
> > > > the current situation.  Because of this problem, just drop the in-kernel
> > > > copy of the ion code now, as it's not used, and is only causing problems
> > > > for everyone involved.
> > > >
> > > > Cc: "Arve Hjønnevåg" <arve@xxxxxxxxxxx>
> > > > Cc: "Christian König" <christian.koenig@xxxxxxx>
> > > > Cc: Christian Brauner <christian@xxxxxxxxxx>
> > > > Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
> > > > Cc: Hridya Valsaraju <hridya@xxxxxxxxxx>
> > > > Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
> > > > Cc: John Stultz <john.stultz@xxxxxxxxxx>
> > > > Cc: Laura Abbott <laura@xxxxxxxxxxxx>
> > > > Cc: Martijn Coenen <maco@xxxxxxxxxxx>
> > > > Cc: Shuah Khan <shuah@xxxxxxxxxx>
> > > > Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> > > > Cc: Suren Baghdasaryan <surenb@xxxxxxxxxx>
> > > > Cc: Todd Kjos <tkjos@xxxxxxxxxxx>
> > > > Cc: devel@xxxxxxxxxxxxxxxxxxxx
> > > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> > > > Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
> > > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> > >
> > > We discussed this at the Android MC on Monday and the plan was to
> > > remove it after the next LTS release.
> >
> > I know it was discussed, my point is that it is actually causing
> > problems now (with developers who want to change the internal kernel api
> > hitting issues, and newbies trying to clean up code in ways that isn't
> > exactly optimal wasting maintainer cycles), and that anyone who uses
> > this code, is not actually using this version of the code.  Everyone who
> > relies on ion right now, is using the version that is in the Android
> > common kernel tree, which has diverged from this in-kernel way quite a
> > bit now for the reason that we didn't want to take any of those new
> > features in the in-kernel version.
> >
> > So this is a problem that we have caused by just wanting to wait, no one
> > is using this code, combined with it causing problems for the upstream
> > developers.
> >
> > There is nothing "magic" about the last kernel of the year that requires
> > this code to sit here until then.  At that point in time, all users
> > will, again, be using the forked Android kernel version, and if we
> > delete this now here, that fork can remain just fine, with the added
> > benifit of it reducing developer workloads here in-kernel.
> >
> > So why wait?
> 
> Hi,
> 
> I don't know what is the right thing to do here. I just want to
> highlight that AOSP's audio (codec2) HAL depends on the ION system
> heap and it will break AOSP for people who boot mainline on their
> devices, even for just testing purpose like we do in Linaro. Right now
> we need only 1 (Android specific out-of-tree) patch to boot AOSP with
> mainline and Sumit is already trying to upstream that vma naming
> patch. Removal of in-kernel ION, will just add more to that delta.

As AOSP will continue to rely on ION after December of this year, all
you are doing is postponing the inevitable a few more months.

Push back on the Android team to fix up the code to not use ION, they
know this needs to happen.

thanks,

greg k-h