Questions about KMS flip

[Daniel Vetter]

On Thu, Nov 04, 2021 at 12:44:34PM -0400, Harry Wentland wrote:
> +Nick
> 
> It looks to be the old drm_plane_state->fb holds that reference. See dm_plane_helper_cleanup_fb() in amdgpu_dm.c.

Yup plane state holds reference for its entire existing (well this holds
in general as design principle for atomic state structs, just makes life
easier). And the plane state is guaranteed to exist from when we first pin
(prepare_fb plane hook) to when it's getting unpinned (cleanup_fb plane
hook).

Out of curiosity, what's blowing up?
-Daniel

> 
> Harry
> 
> On 2021-11-04 08:51, Christian König wrote:
> > Hi guys,
> > 
> > adding the usual suspects which might know that of hand: When we do a KMS page flip, who keeps the reference to the BO while it is scanned out?
> > 
> > We are running into warning backtraces from TTM which look more than odd.
> > 
> > Thanks,
> > Christian.
> 

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch