[Intel-gfx] [PATCH] drm/i915: Recalculate CDCLK if plane scaling ratio changes

[Ville Syrjälä]

On Wed, Jan 12, 2022 at 04:39:17PM +0200, Lisovskiy, Stanislav wrote:
> On Wed, Jan 12, 2022 at 03:50:05PM +0200, Ville Syrjälä wrote:
> > On Tue, Jan 11, 2022 at 06:08:12PM +0200, Stanislav Lisovskiy wrote:
> > > Currently we only recalculate CDCLK if active plane mask changes
> > > or if we do a full modeset, however according to BSpec
> > > required Dbuf bandwidth calculations also depend on pipe/plane
> > > scaling ratio, which means that CDCLK must be recalculated
> > > everytime plane scaling ratio changes,
> > 
> > Already handled by the plane min_cdclk stuff.
> 
> Problem is that plane min_cdclk will only be called for those
> which are added to the state.
> In intel_atomic_check_planes we call intel_crtc_add_planes_to_state
> only if active_planes_affects_min_cdclk is true and active_planes
> mask got changed.
> However if we got one of planes scaling ratio changed, we need to
> recalculate CDCLK once again and make sure we have all the active
> planes in state for that. Don't we need all active planes 
> in state to calculate it properly?

If the plane's scaling ratio is changing then that plane is already
in the state. The min_cdclk/data_rate/etc. are all then cached in
the crtc state so that plane isn't needed again until its scaling
ratio (or whatever else) changes again.

-- 
Ville Syrjälä
Intel