Re: [PATCH v3] drm/tidss: dispc: Rewrite naive plane positioning code

On 13/02/2020 12:44, Jyri Sarha wrote:

• /*

• * If a plane on a CRTC changes add all active planes on that
  

• * CRTC to the atomic state. This is needed for updating the
  

• * plane positions in tidss_crtc_position_planes() which is
  

• * called from crtc_atomic_enable() and crtc_atomic_flush().
  

• * The update is needed for x,y-position changes too, so
  

• * zpos_changed condition is not enough and we need this if
  

• * planes_changed is true too.
  

• */
  

• for_each_new_crtc_in_state(state, crtc, cstate, i) {

• if (cstate->zpos_changed || cstate->planes_changed) {
  

• 	ret = drm_atomic_add_affected_planes(state, crtc);
  

• 	if (ret)
  

• 		return ret;
  

• }
  

• }

I think 99.99...% of the commits are such where only planes' fb address is changed. I think "planes_changed" is true for these. I wonder if it would be a sensible optimization to skip this for those 99.99...% cases. Can we detect that easily?

Well, we haven't optimized for those 99.99...% cases anywhere else either, so it's possible it doesn't matter.

Tomi