On Wednesday, February 10th, 2021 at 2:16 PM, Daniel Vetter daniel@ffwll.ch wrote:
On Tue, Feb 09, 2021 at 04:14:01PM -0800, Manasi Navare wrote:
These additional checks added to avoid EBUSY give unnecessary WARN_ON in case of big joiner used in i915 in which case even if the modeset is requested on a single pipe, internally another consecutive pipe is stolen and used to drive half of the transcoder timings. So in this case it is expected that requested crtc and affected crtcs do not match. Hence the added WARN ON becomes irrelevant.
The WARN_ON only happens if allow_modeset == false. If allow_modeset == true, then the driver is allowed to steal an unrelated pipe.
Maybe i915 is stealing a pipe without allow_modeset?
Nope. We can maybe rework this so that i915 can do stuff under the hood, but wrt uapi this was the thing we discussed with compositors. Without such a guarantee atomic is defacto broken from a compositor pov.
Agreed.