Re: [PATCH] drm: document and enforce rules around "spurious" EBUSY from atomic_commit

Hi,

On Tue, 22 Sep 2020 at 19:18, Daniel Vetter daniel.vetter@ffwll.ch wrote:

•   for_each_new_crtc_in_state(state, crtc, old_crtc_state, i)
  

•           affected_crtc |= drm_crtc_mask(crtc);
  

•   /*
  

•    * For commits that allow modesets drivers can add other CRTCs to the
  

•    * atomic commit, e.g. when they need to reallocate global resources.
  

•    * This can cause spurious EBUSY, which robs compositors of a very
  

•    * effective sanity check for their drawing loop. Therefor only allow
  

•    * this for modeset commits.
  

•    *
  

•    * FIXME: Should add affected_crtc mask to the ATOMIC IOCTL as an output
  

•    * so compositors know what's going on.
  

•    */
  

•   if (affected_crtc != requested_crtc) {
  

•           /* adding other CRTC is only allowed for modeset commits */
  

•           WARN_ON(!state->allow_modeset);
  

•   }
  

Can we please add a DRM_DEBUG() here, regardless of the WARN_ON(), to let people know what's happening?

With that, R-b me.

Cheers, Daniel