[git pull] drm for 5.8-rc1

[James Jones]

I'll defer to Thierry, but I think that may be by design.  Tegra format 
modifiers were added to get things like this working in the first place, 
right?  It's not a regression, is it?

Thanks,
-James

On 8/13/20 10:19 AM, Karol Herbst wrote:
> 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 at 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 at 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 at 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 at 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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