On Thu, Apr 30, 2020 at 01:05:15PM +0300, Lisovskiy, Stanislav wrote:
> On Thu, Apr 30, 2020 at 12:21:04PM +0300, Ville Syrjälä wrote:
> > On Thu, Apr 23, 2020 at 10:58:56AM +0300, Stanislav Lisovskiy wrote:
> > > We need to calculate SAGV mask also in a non-modeset
> > > commit, however currently active_pipes are only calculated
> > > for modesets in global atomic state, thus now we will be
> > > tracking those also in bw_state in order to be able to
> > > properly access global data.
> > > 
> > > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovs...@intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/display/intel_bw.h |  3 +++
> > >  drivers/gpu/drm/i915/intel_pm.c         | 15 ++++++++++-----
> > >  2 files changed, 13 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/display/intel_bw.h 
> > > b/drivers/gpu/drm/i915/display/intel_bw.h
> > > index d6df91058223..898b4a85ccab 100644
> > > --- a/drivers/gpu/drm/i915/display/intel_bw.h
> > > +++ b/drivers/gpu/drm/i915/display/intel_bw.h
> > > @@ -26,6 +26,9 @@ struct intel_bw_state {
> > >  
> > >   unsigned int data_rate[I915_MAX_PIPES];
> > >   u8 num_active_planes[I915_MAX_PIPES];
> > > +
> > > + /* bitmask of active pipes */
> > > + u8 active_pipes;
> > >  };
> > >  
> > >  #define to_intel_bw_state(x) container_of((x), struct intel_bw_state, 
> > > base)
> > > diff --git a/drivers/gpu/drm/i915/intel_pm.c 
> > > b/drivers/gpu/drm/i915/intel_pm.c
> > > index 7e15cf3368ad..f7249bca3f6f 100644
> > > --- a/drivers/gpu/drm/i915/intel_pm.c
> > > +++ b/drivers/gpu/drm/i915/intel_pm.c
> > > @@ -3874,6 +3874,7 @@ static int intel_compute_sagv_mask(struct 
> > > intel_atomic_state *state)
> > >   struct intel_bw_state *new_bw_state = NULL;
> > >   const struct intel_bw_state *old_bw_state = NULL;
> > >   int i;
> > > + bool active_pipes_calculated = false;
> > >  
> > >   for_each_new_intel_crtc_in_state(state, crtc,
> > >                                    new_crtc_state, i) {
> > > @@ -3883,6 +3884,12 @@ static int intel_compute_sagv_mask(struct 
> > > intel_atomic_state *state)
> > >  
> > >           old_bw_state = intel_atomic_get_old_bw_state(state);
> > >  
> > > +         if (!active_pipes_calculated) {
> > > +                 state->active_pipes = new_bw_state->active_pipes =
> > 
> > I don't think we should touch state->active_pipes here.
> 
> Well, that was my question actually here as well. I understand that changing
> state->active_pipes here feels like some unneeded side effect, however having
> state->active_pipes and bw_state->active_pipes going out of sync doesn't sound
> very attractive to me either. That is why I don't like this idea of 
> duplication
> at all - having constant need to sync those state, bw_state, cdclk_state, 
> because
> they all might have different active_pipes now.

Having an out of date active_pipes anywhere would be a bug in that
specific code. Also state->active_pipes is definitely going the way of
the dodo soon.

> 
> > 
> > > +                         intel_calc_active_pipes(state, 
> > > old_bw_state->active_pipes);
> > > +                 active_pipes_calculated = true;
> > > +         }
> > 
> > I'd do this after the loop so we don't need this extra boolean. As far
> > as the active_pipes check in intel_crtc_can_enable_sagv(), I think we
> > can pull it out into intel_compute_sagv_mask() so that we do the check
> > after computing the mask. And of course change it to use
> > bw_state->active_pipes instead.
> 
> intel_crtc_can_enable_sagv is called per crtc - so can't just pull it out, 
> will have to have to cycles then - one will compute bw_state->active_pipes,
> and another pipe_sagv_mask.

Hmm. Actually I think what we should probably do is keep the
active_pipes check in intel_can_enable_sagv(). Ie something like this:

intel_can_enable_sagv(bw_state) {
        if (active_pipes && !is_power_of_2(active_pipes))
                return false;
        return sagv_reject != 0;
}

compute_sagv() {
        for_each_crtc() {
                if (crtc_can_sagv())
                        sagv_reject &= ~pipe;
                else
                        sagv_reject |= pipe;
        }
        
        active_pipes = calc_active_pipes();

        ... lock/serialize etc.
}

That way we don't have to update sagv_reject at all based on
active_pipes. I think that even makes more sense since the
active_pipes check is a global thing and not tied to any specific
crtc.

We can then make the check conditional on pre-icl (or whatever we want)
in a later patch. And finally we can remove it altogether in a separate
patch, since I don't think we should have to do it on any platform.

> 
> > 
> > We're also going to need to lock_global_state() if bw_state->active_pipes
> > mask changes.
> 
> Ohh.. right.
> 
> 
> Stan
> 
> > 
> > > +
> > >           if (intel_crtc_can_enable_sagv(new_crtc_state))
> > >                   new_bw_state->pipe_sagv_reject &= ~BIT(crtc->pipe);
> > >           else
> > > @@ -5911,11 +5918,9 @@ skl_compute_wm(struct intel_atomic_state *state)
> > >   if (ret)
> > >           return ret;
> > >  
> > > - if (state->modeset) {
> > > -         ret = intel_compute_sagv_mask(state);
> > > -         if (ret)
> > > -                 return ret;
> > > - }
> > > + ret = intel_compute_sagv_mask(state);
> > > + if (ret)
> > > +         return ret;
> > 
> > We also need to remove the state->modeset checks around
> > sagv_{pre,post}_update().
> > 
> > >  
> > >   /*
> > >    * skl_compute_ddb() will have adjusted the final watermarks
> > > -- 
> > > 2.24.1.485.gad05a3d8e5
> > 
> > -- 
> > Ville Syrjälä
> > Intel

-- 
Ville Syrjälä
Intel
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