Re: [git pull] drm for 5.8-rc1

From: Karol Herbst <kherbst@redhat.com>
To: James Jones <jajones@nvidia.com>
Cc: dri-devel <dri-devel@lists.freedesktop.org>,
	Thierry Reding <treding@nvidia.com>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Subject: Re: [git pull] drm for 5.8-rc1
Date: Thu, 13 Aug 2020 19:19:40 +0200	[thread overview]
Message-ID: <CACO55tsEjGUhfrBdbcpT9xLa8N-T0JR-t7xFBA5pxDZ5+NiQhg@mail.gmail.com> (raw)
In-Reply-To: <CACO55tsfV9pGijOF5F=dLqFhpXgPSArGHXa44Mt3eRBk7z-X=g@mail.gmail.com>

another thing: with gsettings set org.gnome.mutter
experimental-features '["kms-modifiers"]' it all just works out of the
box with wayland, but that won't be enabled for quite some time, so we
need to figure out what is broken (less so with my patch) under
wayland with gnome :)

On Thu, Aug 13, 2020 at 5:39 PM Karol Herbst <kherbst@redhat.com> wrote:
>
> btw, I just noticed that wayland with gnome-shell is totally busted.
> With this MR it at least displays something, but without it doesn't
> work at all.
>
> On Thu, Aug 13, 2020 at 3:00 PM Karol Herbst <kherbst@redhat.com> wrote:
> >
> > At least for now I've created an MR to revert the change:
> > https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6300
> >
> > But it seems like there was probably a good reason why it got added?
> > Happy to have better fixes, but that's the best we've got so far I
> > think?
> >
> > Thierry, what do you think?
> >
> > On Wed, Aug 12, 2020 at 8:51 PM Karol Herbst <kherbst@redhat.com> wrote:
> > >
> > > in case you all were wondering, it works on xorg-server git because of
> > > this commit: https://gitlab.freedesktop.org/xorg/xserver/-/commit/9b8999411033c9473cd68e92e4690a91aecf5b95
> > >
> > > On Wed, Aug 12, 2020 at 8:25 PM James Jones <jajones@nvidia.com> wrote:
> > > >
> > > > On 8/12/20 10:40 AM, Alyssa Rosenzweig wrote:
> > > > >> ...and in merging my code with Alyssa's new panfrost format modifier
> > > > >> support, I see panfrost does the opposite of this and treats a format
> > > > >> modifier list of only INVALID as "don't care".  I modeled the new nouveau
> > > > >> behavior on the Iris driver.  Now I'm not sure which is correct :-(
> > > > >
> > > > > ....and neither am I. Uh-oh.
> > > > >
> > > > > I modeled the panfrost code after v3d_resource_create_with_modifiers,
> > > > > which treats INVALID as "don't care". I can confirm the panfrost code
> > > > > works (in the sense that it's functional on the machines I've tested),
> > > > > but I don't know if it is actually correct. I think it is, since
> > > > > otherwise you end up using linear in places it's unnecessary, but I'm
> > > > > not sure where this is spec'd.
> > > >
> > > > It would depend on whether an app actually calls the function this way,
> > > > and whether that app was tested I suppose.  If I'm interpreting the Iris
> > > > code correctly and it doesn't break anything, then I'm assuming both
> > > > implementations are equally valid in that nothing exercises this path,
> > > > but it would be good to have the intended behavior documented somewhere
> > > > so we can try to work towards consistent in case someone tries it in the
> > > > future.
> > > >
> > > > My nouveau change runs afoul of assumptions in the tegra driver, but
> > > > that's easy enough to fix in lockstep if desired.
> > > >
> > > > Also, heads up: I'll ping you on my format modifier cleanup MR once I've
> > > > pushed the latest version.  The panfrost modifier usage was harder to
> > > > merge into the refactoring than most, so it'll be good to have your
> > > > review and if you have time, some testing.  I think I landed on an
> > > > elegant solution, but open to suggestions.
> > > >
> > > > Thanks,
> > > > -James
> > > >

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