On 2020-09-14 5:33 p.m., Kazlauskas, Nicholas wrote:
On 2020-09-14 11:22 a.m., Michel Dänzer wrote:
On 2020-09-14 4:37 p.m., Kazlauskas, Nicholas wrote:
On 2020-09-14 3:52 a.m., Michel Dänzer wrote:
P.S. Since DCN doesn't make a distinction between primary or overlay
planes in hardware, could ChromiumOS achieve the same effect with
only the primary plane instead of only an overlay plane? If so,
maybe there's no need for the "black plane hack".
I only know that atomictest tries to enable this configuration. Not
sure if ChromiumOS or other "real" userspace tries this configuration.
Someone mentioned that ChromiumOS uses this for video playback with
black bars (when the video aspect ratio doesn't match the display's).
We only expose support for NV12 on the primary plane so we wouldn't be
hitting this case at least.
Interesting, so if we're lucky this really won't affect any real-world apps.
We can always go back to lying to userspace about the cursor being
visible if the commit fails in that case I guess [...]
I'm not sure what you mean by that / how it could work.
Dropping the check you added in this patch:
+ if (state->enable &&
+ !(state->plane_mask & drm_plane_mask(crtc->primary)))
return -EINVAL;
That way we can still allow the cursor plane to be enabled while
primary/overlay are not, it's just not going to be actually visible on
the screen. It'll fail some IGT tests but nothing really uses this
configuration as more than just a temporary state.
As Daniel pointed out in <20200901075432.GW2352366@phenom.ffwll.local>
in the v1 patch thread, that won't fly, since atomic userspace can
legitimately expect the cursor plane to be visible in that case.
--
Earthling Michel Dänzer | https://redhat.com
Libre software enthusiast | Mesa and X developer
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