[Intel-gfx] [PATCH 08/17] drm/plane-helper: transitional atomic plane helpers

[Daniel Vetter]

On Wed, Nov 5, 2014 at 5:45 PM, Sean Paul <seanpaul at chromium.org> wrote:
>> + /* There's no other way to figure out whether the crtc is running. */
>> + ret = drm_crtc_vblank_get(crtc[i]);
>> + if (ret == 0) {
>> + drm_crtc_wait_one_vblank(crtc[i]);
>> + drm_crtc_vblank_put(crtc[i]);
>> + }
>
> This will be good motivation for driver writers to convert to universal
> planes!

The problem here is actually dpms. Our current dpms interface sucks
badly, since from generic code it's completely impossible to figure
out whether the pipe is still on or somehow disabled due to dpms. I'm
pondering ideas and designs right now, but my current dpms plan for
atomic includes a fix for this. So with that I'd replace this hack
with crtc->state->active check and add a WARN_ON to make sure the
drm_vblank_get doesn't fail when the pipe is supposed to be on.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch