[Intel-gfx] Merging TTM branches through the Intel tree?

[Daniel Vetter]

On Thu, Jun 3, 2021 at 8:50 AM Thomas Hellström
<thomas.hellstrom at linux.intel.com> wrote:
>
>
> On 6/2/21 8:40 PM, Daniel Vetter wrote:
> > On Wed, Jun 02, 2021 at 11:48:41AM +0200, Christian König wrote:
> >> Am 02.06.21 um 11:16 schrieb Thomas Hellström (Intel):
> >>> On 6/2/21 10:32 AM, Christian König wrote:
> >>>> Uff I'm just waiting for feedback from Philip to merge a large patch
> >>>> set for TTM through drm-misc-next.
> >>>>
> >>>> I'm pretty sure we will run into merge conflicts if you try to push
> >>>> your changes through the Intel tree.
> >>>>
> >>>> Christian.
> >>> OK, so what would be the best approach here?, Adding the TTM patches to
> >>> drm-misc-next when your set has landed?
> >> I think I will send out out my set to Matthew once more for review, then
> >> push the common TTM stuff to drm-misc-next as much as possible.
> >>
> >> Then you should be able to land your stuff to drm-misc-next and rebase on
> >> the end result.
> >>
> >> Just need to note to David that drm-misc-next should be merged to drm-next
> >> before the Intel patches depending on that stuff land as well.
> > Other option (because the backmerges tend to be slow) is a topic branch,
> > and we just eat/resolve the conflicts in both drm-misc-next and
> > drm-intel-gt-next in the merge commit. If it's not too bad (I haven't
> > looked at what exactly we need for the i915 side from ttm in detail).
> >
> > But also often figuring out the topic branch logistics takes longer than
> > just merging to drm-misc-next as the patches get ready.
> > -Daniel
>
> Daniel: So the thing we need to get into TTM is the iterator-based
> move_memcpy which is more adaptable than the current one and needed to
> support non-linear lmem buffers, some bug-fixes and minor changes to be
> able to keep our short-term-pinning while on the LRU. A necessary evil.
>
> Christian: it looks like you have landed some TTM changes already, in
> particular the &bo->mem -> bo->resource change which is the main
> conflict I think. Is the 10 patches self-allocation series the main
> remaining part? That will probably cause some conflicts with already
> pushed i915 TTM setup code, but otherwise will not conflict with the
> rest of the TTM code I think, which should make it possible to bring in
> our TTM changes after conflict resolution with what you've already
> pushed. The memcpy code is pretty self-contained.

I think in that case topic branch on top of drm-next (once the ttm
bits we conflict with are there) is probably best, and then pull that
into drm-misc-next and drm-intel-gt-next. Merge window freeze is also
approach, so without topic branch we'd be stuck until like -rc2 when
drm-next reopens. I guess Maarten can do the topic branch logistics in
drm-misc.git for this.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch