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 <3d8de519-65b3-123b-8ace-e820982884e0@labbott.name> <20200827160506.GC684514@kroah.com>
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From:   Amit Pundir <amit.pundir@linaro.org>
Date:   Thu, 27 Aug 2020 22:31:41 +0530
Message-ID: <CAMi1Hd1Ch1RWvOTnON3tsrucaKThTuGQnwNFo94GqUjufVmnOg@mail.gmail.com>
Subject: Re: [PATCH] staging: ion: remove from the tree
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Laura Abbott <laura@labbott.name>,
        Sumit Semwal <sumit.semwal@linaro.org>,
        John Stultz <john.stultz@linaro.org>,
        "open list:ANDROID DRIVERS" <devel@driverdev.osuosl.org>,
        linaro-mm-sig@lists.linaro.org, Shuah Khan <shuah@kernel.org>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        lkml <linux-kernel@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Suren Baghdasaryan <surenb@google.com>,
        Christoph Hellwig <hch@infradead.org>,
        Joel Fernandes <joel@joelfernandes.org>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        Hridya Valsaraju <hridya@google.com>,
        Android Kernel Team <kernel-team@android.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        Christian Brauner <christian@brauner.io>
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On Thu, 27 Aug 2020 at 21:34, Greg Kroah-Hartman
<gregkh@linuxfoundation.org> 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 diverge=
d
> > > 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 i=
n
> > > 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 a=
t
> > > the current situation.  Because of this problem, just drop the in-ker=
nel
> > > copy of the ion code now, as it's not used, and is only causing probl=
ems
> > > for everyone involved.
> > >
> > > Cc: "Arve Hj=C3=B8nnev=C3=A5g" <arve@android.com>
> > > Cc: "Christian K=C3=B6nig" <christian.koenig@amd.com>
> > > Cc: Christian Brauner <christian@brauner.io>
> > > Cc: Christoph Hellwig <hch@infradead.org>
> > > Cc: Hridya Valsaraju <hridya@google.com>
> > > Cc: Joel Fernandes <joel@joelfernandes.org>
> > > Cc: John Stultz <john.stultz@linaro.org>
> > > Cc: Laura Abbott <laura@labbott.name>
> > > Cc: Martijn Coenen <maco@android.com>
> > > Cc: Shuah Khan <shuah@kernel.org>
> > > Cc: Sumit Semwal <sumit.semwal@linaro.org>
> > > Cc: Suren Baghdasaryan <surenb@google.com>
> > > Cc: Todd Kjos <tkjos@android.com>
> > > Cc: devel@driverdev.osuosl.org
> > > Cc: dri-devel@lists.freedesktop.org
> > > Cc: linaro-mm-sig@lists.linaro.org
> > > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> >
> > 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.

Regards,
Amit Pundir

>
> thanks,
>
> greg k-h