On Tue, Dec 11, 2018 at 05:59:56PM +0200, Ville Syrjälä wrote:
> On Mon, Dec 10, 2018 at 05:05:43PM -0800, Matt Roper wrote:
...snip...
> >  
> > -   alloc_size -= total_min_blocks;
> > -   cstate->wm.skl.plane_ddb_y[PLANE_CURSOR].start = alloc->end - 
> > minimum[PLANE_CURSOR];
> > -   cstate->wm.skl.plane_ddb_y[PLANE_CURSOR].end = alloc->end;
> > -
> >     /*
> > -    * 2. Distribute the remaining space in proportion to the amount of
> > -    * data each plane needs to fetch from memory.
> > -    *
> > -    * FIXME: we may not allocate every single block here.
> > +    * Grant each plane the blocks it requires at the highest achievable
> > +    * watermark level, plus an extra share of the leftover blocks
> > +    * proportional to its relative data rate.
> >      */
> > -   if (total_data_rate == 0)
> > -           return 0;
> > -
> > -   start = alloc->start;
> >     for_each_plane_id_on_crtc(intel_crtc, plane_id) {
> > -           u64 data_rate, uv_data_rate;
> > -           uint16_t plane_blocks, uv_plane_blocks;
> > +           u64 rate;
> > +           u16 extra;
> >  
> >             if (plane_id == PLANE_CURSOR)
> >                     continue;
> > +           if (alloc_size == 0)
> > +                   continue;
> 
> This seems wrong. We wouldn't assign anything to total/uv_total for the
> plane in this case. I guess you could move those assignments to the
> earlier loop and then s/continue/break/ here? Or we just remove the
> continue entirely and let the calculations go through even if
> alloc_size==0.

It should probably be a break, since we'll only hit this on a loop
iteration where we've handed the whole pipe allocation and all remaining
planes are disabled.  The total and uv_total were initialized to 0 at
initialization time, so that should be correct for all remaining planes.

Also, we can't let the calculation proceed here, otherwise we'll divide
by 0 (total_data_rate) farther down since that value also decreases with
each loop iteration.


Matt

> 
> >  
> > -           data_rate = plane_data_rate[plane_id];
> > +           wm = &cstate->wm.skl.optimal.planes[plane_id];
> >  
> > -           /*
> > -            * allocation for (packed formats) or (uv-plane part of planar 
> > format):
> > -            * promote the expression to 64 bits to avoid overflowing, the
> > -            * result is < available as data_rate / total_data_rate < 1
> > -            */
> > -           plane_blocks = minimum[plane_id];
> > -           plane_blocks += div64_u64(alloc_size * data_rate, 
> > total_data_rate);
> > +           rate = plane_data_rate[plane_id];
> > +           extra = min_t(u16, alloc_size,
> > +                         DIV_ROUND_UP(alloc_size * rate, total_data_rate));
> > +           total[plane_id] = wm->wm[level].plane_res_b + extra;
> > +           alloc_size -= extra;
> > +           total_data_rate -= rate;
> >  
> > -           /* Leave disabled planes at (0,0) */
> > -           if (data_rate) {
> > -                   cstate->wm.skl.plane_ddb_y[plane_id].start = start;
> > -                   cstate->wm.skl.plane_ddb_y[plane_id].end = start + 
> > plane_blocks;
> > -           }
> > +           if (alloc_size == 0)
> > +                   continue;
> >  
> > -           start += plane_blocks;
> > +           rate = uv_plane_data_rate[plane_id];
> > +           extra = min_t(u16, alloc_size,
> > +                         DIV_ROUND_UP(alloc_size * rate, total_data_rate));
> > +           uv_total[plane_id] = wm->uv_wm[level].plane_res_b + extra;
> > +           alloc_size -= extra;
> > +           total_data_rate -= rate;
> > +   }
> > +   WARN_ON(alloc_size != 0 || total_data_rate != 0);
> >  
> > -           /* Allocate DDB for UV plane for planar format/NV12 */
> > -           uv_data_rate = uv_plane_data_rate[plane_id];
> > +   /* Set the actual DDB start/end points for each plane */
> > +   start = alloc->start;
> > +   for_each_plane_id_on_crtc(intel_crtc, plane_id) {
> > +           struct skl_ddb_entry *plane_alloc, *uv_plane_alloc;
> >  
> > -           uv_plane_blocks = uv_minimum[plane_id];
> > -           uv_plane_blocks += div64_u64(alloc_size * uv_data_rate, 
> > total_data_rate);
> > +           if (plane_id == PLANE_CURSOR)
> > +                   continue;
> > +
> > +           plane_alloc = &cstate->wm.skl.plane_ddb_y[plane_id];
> > +           uv_plane_alloc = &cstate->wm.skl.plane_ddb_uv[plane_id];
> >  
> >             /* Gen11+ uses a separate plane for UV watermarks */
> > -           WARN_ON(INTEL_GEN(dev_priv) >= 11 && uv_plane_blocks);
> > +           WARN_ON(INTEL_GEN(dev_priv) >= 11 && uv_total[plane_id]);
> > +
> > +           /* Leave disabled planes at (0,0) */
> > +           if (total[plane_id]) {
> > +                   plane_alloc->start = start;
> > +                   plane_alloc->end = start += total[plane_id];
> > +           }
> >  
> > -           if (uv_data_rate) {
> > -                   cstate->wm.skl.plane_ddb_uv[plane_id].start = start;
> > -                   cstate->wm.skl.plane_ddb_uv[plane_id].end =
> > -                           start + uv_plane_blocks;
> > +           if (uv_total[plane_id]) {
> > +                   uv_plane_alloc->start = start;
> > +                   uv_plane_alloc->end = start + uv_total[plane_id];
> >             }
> > +   }
> >  
> > -           start += uv_plane_blocks;
> > +   /*
> > +    * When we calculated watermark values we didn't know how high
> > +    * of a level we'd actually be able to hit, so we just marked
> > +    * all levels as "enabled."  Go back now and disable the ones
> > +    * that aren't actually possible.
> > +    */
> > +   for (level++; level <= ilk_wm_max_level(dev_priv); level++) {
> > +           for_each_plane_id_on_crtc(intel_crtc, plane_id) {
> > +                   wm = &cstate->wm.skl.optimal.planes[plane_id];
> > +                   memset(&wm->wm[level], 0, sizeof(wm->wm[level]));
> > +           }
> > +   }
> > +
> > +   /*
> > +    * Go back and disable the transition watermark if it turns out we
> > +    * don't have enough DDB blocks for it.
> > +    */
> > +   for_each_plane_id_on_crtc(intel_crtc, plane_id) {
> > +           wm = &cstate->wm.skl.optimal.planes[plane_id];
> > +           if (wm->trans_wm.plane_res_b > total[plane_id])
> > +                   memset(&wm->trans_wm, 0, sizeof(wm->trans_wm));
> >     }
> >  
> >     return 0;
> > @@ -4715,17 +4665,15 @@ skl_compute_plane_wm_params(const struct 
> > intel_crtc_state *cstate,
> >     return 0;
> >  }
> >  
> > -static int skl_compute_plane_wm(const struct intel_crtc_state *cstate,
> > -                           const struct intel_plane_state *intel_pstate,
> > -                           uint16_t ddb_allocation,
> > -                           int level,
> > -                           const struct skl_wm_params *wp,
> > -                           const struct skl_wm_level *result_prev,
> > -                           struct skl_wm_level *result /* out */)
> > +static void skl_compute_plane_wm(const struct intel_crtc_state *cstate,
> > +                            const struct intel_plane_state *intel_pstate,
> > +                            int level,
> > +                            const struct skl_wm_params *wp,
> > +                            const struct skl_wm_level *result_prev,
> > +                            struct skl_wm_level *result /* out */)
> >  {
> >     struct drm_i915_private *dev_priv =
> >             to_i915(intel_pstate->base.plane->dev);
> > -   const struct drm_plane_state *pstate = &intel_pstate->base;
> >     uint32_t latency = dev_priv->wm.skl_latency[level];
> >     uint_fixed_16_16_t method1, method2;
> >     uint_fixed_16_16_t selected_result;
> > @@ -4733,10 +4681,6 @@ static int skl_compute_plane_wm(const struct 
> > intel_crtc_state *cstate,
> >     struct intel_atomic_state *state =
> >             to_intel_atomic_state(cstate->base.state);
> >     bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
> > -   uint32_t min_disp_buf_needed;
> > -
> > -   if (latency == 0)
> > -           return level == 0 ? -EINVAL : 0;
> >  
> >     /* Display WA #1141: kbl,cfl */
> >     if ((IS_KABYLAKE(dev_priv) || IS_COFFEELAKE(dev_priv) ||
> > @@ -4800,61 +4744,24 @@ static int skl_compute_plane_wm(const struct 
> > intel_crtc_state *cstate,
> >                     res_blocks = result_prev->plane_res_b;
> >     }
> >  
> > -   if (INTEL_GEN(dev_priv) >= 11) {
> > -           if (wp->y_tiled) {
> > -                   uint32_t extra_lines;
> > -                   uint_fixed_16_16_t fp_min_disp_buf_needed;
> > -
> > -                   if (res_lines % wp->y_min_scanlines == 0)
> > -                           extra_lines = wp->y_min_scanlines;
> > -                   else
> > -                           extra_lines = wp->y_min_scanlines * 2 -
> > -                                         res_lines % wp->y_min_scanlines;
> > -
> > -                   fp_min_disp_buf_needed = mul_u32_fixed16(res_lines +
> > -                                           extra_lines,
> > -                                           wp->plane_blocks_per_line);
> > -                   min_disp_buf_needed = fixed16_to_u32_round_up(
> > -                                           fp_min_disp_buf_needed);
> > -           } else {
> > -                   min_disp_buf_needed = DIV_ROUND_UP(res_blocks * 11, 10);
> > -           }
> > -   } else {
> > -           min_disp_buf_needed = res_blocks;
> > -   }
> > -
> > -   if ((level > 0 && res_lines > 31) ||
> > -       res_blocks >= ddb_allocation ||
> > -       min_disp_buf_needed >= ddb_allocation) {
> > -           /*
> > -            * If there are no valid level 0 watermarks, then we can't
> > -            * support this display configuration.
> > -            */
> > -           if (level) {
> > -                   return 0;
> > -           } else {
> > -                   struct drm_plane *plane = pstate->plane;
> > -
> > -                   DRM_DEBUG_KMS("Requested display configuration exceeds 
> > system watermark limitations\n");
> > -                   DRM_DEBUG_KMS("[PLANE:%d:%s] blocks required = %u/%u, 
> > lines required = %u/31\n",
> > -                                 plane->base.id, plane->name,
> > -                                 res_blocks, ddb_allocation, res_lines);
> > -                   return -EINVAL;
> > -           }
> > -   }
> > -
> >     /* The number of lines are ignored for the level 0 watermark. */
> > +   if (level > 0 && res_lines > 31)
> > +           return;
> > +
> > +   /*
> > +    * If res_lines is valid, assume we can use this watermark level
> > +    * for now.  We'll come back and disable it after we calculate the
> > +    * DDB allocation if it turns out we don't actually have enough
> > +    * blocks to satisfy it.
> > +    */
> >     result->plane_res_b = res_blocks;
> >     result->plane_res_l = res_lines;
> >     result->plane_en = true;
> > -
> > -   return 0;
> >  }
> >  
> > -static int
> > +static void
> >  skl_compute_wm_levels(const struct intel_crtc_state *cstate,
> >                   const struct intel_plane_state *intel_pstate,
> > -                 uint16_t ddb_blocks,
> >                   const struct skl_wm_params *wm_params,
> >                   struct skl_wm_level *levels)
> >  {
> > @@ -4862,25 +4769,15 @@ skl_compute_wm_levels(const struct intel_crtc_state 
> > *cstate,
> >             to_i915(intel_pstate->base.plane->dev);
> >     int level, max_level = ilk_wm_max_level(dev_priv);
> >     struct skl_wm_level *result_prev = &levels[0];
> > -   int ret;
> >  
> >     for (level = 0; level <= max_level; level++) {
> >             struct skl_wm_level *result = &levels[level];
> >  
> > -           ret = skl_compute_plane_wm(cstate,
> > -                                      intel_pstate,
> > -                                      ddb_blocks,
> > -                                      level,
> > -                                      wm_params,
> > -                                      result_prev,
> > -                                      result);
> > -           if (ret)
> > -                   return ret;
> > +           skl_compute_plane_wm(cstate, intel_pstate, level, wm_params,
> > +                                result_prev, result);
> >  
> >             result_prev = result;
> >     }
> > -
> > -   return 0;
> >  }
> >  
> >  static uint32_t
> > @@ -4908,8 +4805,7 @@ skl_compute_linetime_wm(const struct intel_crtc_state 
> > *cstate)
> >  
> >  static void skl_compute_transition_wm(const struct intel_crtc_state 
> > *cstate,
> >                                   const struct skl_wm_params *wp,
> > -                                 struct skl_plane_wm *wm,
> > -                                 uint16_t ddb_allocation)
> > +                                 struct skl_plane_wm *wm)
> >  {
> >     struct drm_device *dev = cstate->base.crtc->dev;
> >     const struct drm_i915_private *dev_priv = to_i915(dev);
> > @@ -4957,12 +4853,13 @@ static void skl_compute_transition_wm(const struct 
> > intel_crtc_state *cstate,
> >  
> >     }
> >  
> > -   res_blocks += 1;
> > -
> > -   if (res_blocks < ddb_allocation) {
> > -           wm->trans_wm.plane_res_b = res_blocks;
> > -           wm->trans_wm.plane_en = true;
> > -   }
> > +   /*
> > +    * Just assume we can enable the transition watermark.  After
> > +    * computing the DDB we'll come back and disable it if that
> > +    * assumption turns out to be false.
> > +    */
> > +   wm->trans_wm.plane_res_b = res_blocks + 1;
> > +   wm->trans_wm.plane_en = true;
> >  }
> >  
> >  static int skl_build_plane_wm_single(struct intel_crtc_state *crtc_state,
> > @@ -4970,7 +4867,6 @@ static int skl_build_plane_wm_single(struct 
> > intel_crtc_state *crtc_state,
> >                                  enum plane_id plane_id, int color_plane)
> >  {
> >     struct skl_plane_wm *wm = &crtc_state->wm.skl.optimal.planes[plane_id];
> > -   u16 ddb_blocks = 
> > skl_ddb_entry_size(&crtc_state->wm.skl.plane_ddb_y[plane_id]);
> >     struct skl_wm_params wm_params;
> >     int ret;
> >  
> > @@ -4979,12 +4875,8 @@ static int skl_build_plane_wm_single(struct 
> > intel_crtc_state *crtc_state,
> >     if (ret)
> >             return ret;
> >  
> > -   ret = skl_compute_wm_levels(crtc_state, plane_state,
> > -                               ddb_blocks, &wm_params, wm->wm);
> > -   if (ret)
> > -           return ret;
> > -
> > -   skl_compute_transition_wm(crtc_state, &wm_params, wm, ddb_blocks);
> > +   skl_compute_wm_levels(crtc_state, plane_state, &wm_params, wm->wm);
> > +   skl_compute_transition_wm(crtc_state, &wm_params, wm);
> >  
> >     return 0;
> >  }
> > @@ -4994,7 +4886,6 @@ static int skl_build_plane_wm_uv(struct 
> > intel_crtc_state *crtc_state,
> >                              enum plane_id plane_id)
> >  {
> >     struct skl_plane_wm *wm = &crtc_state->wm.skl.optimal.planes[plane_id];
> > -   u16 ddb_blocks = 
> > skl_ddb_entry_size(&crtc_state->wm.skl.plane_ddb_uv[plane_id]);
> >     struct skl_wm_params wm_params;
> >     int ret;
> >  
> > @@ -5006,10 +4897,7 @@ static int skl_build_plane_wm_uv(struct 
> > intel_crtc_state *crtc_state,
> >     if (ret)
> >             return ret;
> >  
> > -   ret = skl_compute_wm_levels(crtc_state, plane_state,
> > -                               ddb_blocks, &wm_params, wm->uv_wm);
> > -   if (ret)
> > -           return ret;
> > +   skl_compute_wm_levels(crtc_state, plane_state, &wm_params, wm->uv_wm);
> >  
> >     return 0;
> >  }
> > @@ -5521,13 +5409,9 @@ skl_compute_wm(struct intel_atomic_state *state)
> >     if (ret || !changed)
> >             return ret;
> >  
> > -   ret = skl_compute_ddb(state);
> > -   if (ret)
> > -           return ret;
> > -
> >     /*
> >      * Calculate WM's for all pipes that are part of this transaction.
> > -    * Note that the DDB allocation above may have added more CRTC's that
> > +    * Note that skl_ddb_add_affected_pipes may have added more CRTC's that
> >      * weren't otherwise being modified (and set bits in dirty_pipes) if
> >      * pipe allocations had to change.
> >      */
> > @@ -5549,6 +5433,10 @@ skl_compute_wm(struct intel_atomic_state *state)
> >                     results->dirty_pipes |= drm_crtc_mask(&crtc->base);
> >     }
> >  
> > +   ret = skl_compute_ddb(state);
> > +   if (ret)
> > +           return ret;
> > +
> >     skl_print_wm_changes(state);
> >  
> >     return 0;
> > -- 
> > 2.14.4
> 
> -- 
> Ville Syrjälä
> Intel

-- 
Matt Roper
Graphics Software Engineer
IoTG Platform Enabling & Development
Intel Corporation
(916) 356-2795
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