On Thu, 2019-10-17 at 14:53 -0700, James Ausmus wrote:
> On Tue, Oct 15, 2019 at 04:50:12PM +0300, Stanislav Lisovskiy wrote:
> > Currently intel_can_enable_sagv function contains
> > a mix of workarounds for different platforms
> > some of them are not valid for gens >= 11 already,
> > so lets split it into separate functions.
> >
> > Signed-off-by: Stanislav Lisovskiy <stanislav.lisovskiy@xxxxxxxxx>
> > Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxx>
> > Cc: James Ausmus <james.ausmus@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/intel_pm.c | 73
> > +++++++++++++++++++++++++++++++--
> > 1 file changed, 70 insertions(+), 3 deletions(-)
> >
> > +bool icl_can_enable_sagv(struct intel_atomic_state *state)
> > +{
> > + struct drm_device *dev = state->base.dev;
> > + struct drm_i915_private *dev_priv = to_i915(dev);
> > + struct intel_crtc *crtc;
> > + struct intel_crtc_state *new_crtc_state;
> > + int level, latency;
> > + int i;
> > + int plane_id;
> > +
> > + if (!intel_has_sagv(dev_priv))
> > + return false;
> > +
> > + /*
> > + * If there are no active CRTCs, no additional checks need be
> > performed
> > + */
> > + if (hweight8(state->active_pipes) == 0)
> > + return true;
> > +
> > + for_each_new_intel_crtc_in_state(state, crtc,
> > + new_crtc_state, i) {
> > +
> > + if (crtc->base.state->adjusted_mode.flags &
> > DRM_MODE_FLAG_INTERLACE)
> > + return false;
> > +
> > + if (!new_crtc_state->base.enable)
> > + continue;
> > +
> > + for_each_plane_id_on_crtc(crtc, plane_id) {
> > + struct skl_plane_wm *wm =
> > + &new_crtc_state-
> > >wm.skl.optimal.planes[plane_id];
> > +
> > + /* Skip this plane if it's not enabled */
> > + if (!wm->wm[0].plane_en)
> > + continue;
> > +
> > + /* Find the highest enabled wm level for this
> > plane */
> > + for (level = ilk_wm_max_level(dev_priv);
> > + !wm->wm[level].plane_en; --level)
> > + { }
> > +
> > + latency = dev_priv->wm.skl_latency[level];
>
> This isn't exactly the same for TGL. From BSpec 49325, "Calculate
> watermark level 0 with level 0 latency + SAGV block time. If the
> result
> can be supported (does not exceed maximum), then the plane can
> tolerate
> SAGV", so I think it can be simplified for Gen12+ by not having to
> loop
> through all the wm levels.
>
> -James
Yes, we discussed that with Ville as I understood, properly doing
that for TGL requires changes to watermark/ddb allocation algorithm,
so that we check if dbuf can fit Level 0 watermark increased by SAGV
block time. I was not sure whether should I add this patch to this
series or proceed with that separately, probably this is worth adding
here - however then it would require changes to watermark algorithm,
as we need to recalculate min_ddb_alloc for Level 0 latency + SAGV
and then check if we fit into DBuf again.
So basically we'll have to calculate watermark level 0 twice - once for
SAGV enabled and once for SAGV disabled case, I would probably do it
already during watermark calculations not when checking bandwidth and
then set some "SAGV can enable" flag, which will be then used by
intel_can_enable_sagv, so that we act accordingly when
bandwidth check and restricting qgv points happens. For pre-gen 12 it
will otherwise use the old algorithm.
>
> > +
> > + /*
> > + * If any of the planes on this pipe don't
> > enable wm levels that
> > + * incur memory latencies higher than
> > sagv_block_time_us we
> > + * can't enable SAGV.
> > + */
> > + if (latency < dev_priv->sagv_block_time_us)
> > + return false;
> > + }
> > + }
> > +
> > + return true;
> > +}
> > +
> > +bool intel_can_enable_sagv(struct intel_atomic_state *state)
> > +{
> > + struct drm_device *dev = state->base.dev;
> > + struct drm_i915_private *dev_priv = to_i915(dev);
> > +
> > + if (INTEL_GEN(dev_priv) >= 11)
> > + return icl_can_enable_sagv(state);
> > +
> > + return skl_can_enable_sagv(state);
> > +}
> > +
> > static u16 intel_get_ddb_size(struct drm_i915_private *dev_priv,
> > const struct intel_crtc_state
> > *crtc_state,
> > const u64 total_data_rate,
> > --
> > 2.17.1
> >
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