[Letux-kernel] jz4730

Paul Boddie paul at boddie.org.uk
Tue Jun 30 22:36:01 CEST 2020

On Tuesday, 30 June 2020 08:04:09 CEST H. Nikolaus Schaller wrote:
> > Am 30.06.2020 um 00:22 schrieb Paul Boddie <paul at boddie.org.uk>:
> > 
> > You may have to remind me what I should be checking out and pulling from
> > since I don't remember and couldn't find it readily in my mails. I have
> > cloned the letux-kernel repository but the origin/master branch seems to
> > be tracking Linux 4.19.
> Yes, the "master" branch follows the latest good enough "stable" tree and is
> not related to the latest work in progress.


> > I did think that since I was going to review everything, I should start
> > with a very recent kernel, hence the decision to choose something in
> > torvalds/linux instead of continuing with the origin/letux/jz4730-v2
> > branch in letux-kernel.
> There are latest branches as e.g. letux-5.8-rc1 or letux-5.8-rc3 but they
> are composed like linux-next from components (ca. 50 feature/topic branches
> to get patch sets for single topics).
> This is done by a script Letux/scripts/merge and its associated
> Letux/scripts/mergefile.
> I did have a nice picture some years ago but could not find it quickly.
> What is missing is a fix to make letux/jz4730 part of that.

It sounds quite complicated, really. I think I would be most efficient working 
with a complete set of patches that can then be split into topics if 
appropriate. Of course, if JZ4730 support is just one topic, then there would 
be only one patchset to work on and to submit, but I think that even device 
tree definitions end up going down a different channel, necessitating the 
independent stewardship of different collections of changes.


> > As communicated in other messages, I did update and test recent Linux
> > kernel code in order to try and get the CI20 HDMI to work, but the last
> > mysterious piece of the puzzle (specific to Linux since it works in L4Re)
> > needs to be found and applied.
> Well, I wasn't able to pick or compile your latest code - and worse, the
> CI20 doesn't boot any more with v5.8-rc1 or letux-5.8-rc1 (even without
> your latest patches).

I neglected to include the device tree files, which would be an obstacle, but 
the patches I made are applied against this changeset in torvalds/linux:

commit b3a9e3b9622ae10064826dccb4f7a52bd88c7407 (tag: v5.8-rc1)
Author: Linus Torvalds <torvalds at linux-foundation.org>
Date:   Sun Jun 14 12:45:04 2020 -0700

    Linux 5.8-rc1

If they don't apply then maybe I did something wrong again.

> > So, I am sorry not to have made any progress as such, but I thought that I
> > should communicate an intent to resume the review of the JZ4730 code when
> > time and energy permit.
> Letux feature branches are merged into letux-5.8. They must be (re)based on
> v5.8-rc1 (or later) to be valid patch sets for upstream submission.

Right. This is probably a good idea.

> Unfortunately I could not rebase
> https://git.goldelico.com/?p=letux-kernel.git;a=shortlog;h=refs/heads/letux/
> jz4730-v2 to v5.8-rc1 and make it compile. So it is still based on v5.7.
> And I had to drop letux/jz4730-v2 from the merge process to not stop other
> architectures. The trick was to create a letux/jz4730-v3 which is (almost)
> identical to what Linus provides upstream. Sort of "add 0".
> You can also see it like removing some staging repo from integration into
> linux-next.
> So the task we should discuss is:
> git checkout -b letux/jz4730-v4 letux/jz4730-v2
> git rebase v5.8-rc1	# or -rc3
> this fails with a lot of rebase conflicts
> fix issues (I do not understand the jz4730 well enough to do it myself)
> git checkout -B temp
> git merge letux-5.8-rc3	# this should now work and build w/o issues

I think that the best way forward for JZ4730 is to rework the patches 
entirely. Several things are now rather different in the kernel, and there 
will be things in our old patches that are now superfluous.


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