This patch implemnets Workariunds related to display arbitrated memory
bandwidth. These WA are applicabe for all gen-9 based platforms.

Changes since v1:
 - Rebase on top of Paulo's patch series
Changes since v2:
 - Address review comments
 - Rebase/rework as per other patch changes in series
Changes since v3:
 - Rework based on Maarten's comments

Signed-off-by: Mahesh Kumar <mahesh1.ku...@intel.com>
---
 drivers/gpu/drm/i915/i915_drv.h      |  11 +++
 drivers/gpu/drm/i915/intel_display.c |  24 ++++++
 drivers/gpu/drm/i915/intel_pm.c      | 155 +++++++++++++++++++++++++++++++++--
 3 files changed, 181 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 69213a4..3126259 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1216,6 +1216,13 @@ enum intel_sbi_destination {
        SBI_MPHY,
 };
 
+/* SKL+ Watermark arbitrated display bandwidth Workarounds */
+enum watermark_memory_wa {
+       WATERMARK_WA_NONE,
+       WATERMARK_WA_X_TILED,
+       WATERMARK_WA_Y_TILED,
+};
+
 #define QUIRK_PIPEA_FORCE (1<<0)
 #define QUIRK_LVDS_SSC_DISABLE (1<<1)
 #define QUIRK_INVERT_BRIGHTNESS (1<<2)
@@ -1788,6 +1795,10 @@ struct skl_ddb_allocation {
 
 struct skl_wm_values {
        unsigned dirty_pipes;
+       /* any WaterMark memory workaround Required */
+       enum watermark_memory_wa mem_wa;
+       uint32_t pipe_bw_kbps[I915_MAX_PIPES];
+       bool pipe_ytiled[I915_MAX_PIPES];
        struct skl_ddb_allocation ddb;
 };
 
diff --git a/drivers/gpu/drm/i915/intel_display.c 
b/drivers/gpu/drm/i915/intel_display.c
index 5d11002..f8da488 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -14574,6 +14574,28 @@ static void intel_atomic_track_fbs(struct 
drm_atomic_state *state)
                                  to_intel_plane(plane)->frontbuffer_bit);
 }
 
+static void
+intel_update_wm_bw_wa(struct drm_atomic_state *state)
+{
+       struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
+       struct drm_i915_private *dev_priv = to_i915(state->dev);
+       const struct drm_crtc *crtc;
+       const struct drm_crtc_state *cstate;
+       struct skl_wm_values *results = &intel_state->wm_results;
+       struct skl_wm_values *hw_vals = &dev_priv->wm.skl_hw;
+       int i;
+
+       if (!IS_GEN9(dev_priv))
+               return;
+
+       for_each_crtc_in_state(state, crtc, cstate, i) {
+               hw_vals->pipe_bw_kbps[i] = results->pipe_bw_kbps[i];
+               hw_vals->pipe_ytiled[i] = results->pipe_ytiled[i];
+       }
+
+       hw_vals->mem_wa = results->mem_wa;
+}
+
 /**
  * intel_atomic_commit - commit validated state object
  * @dev: DRM device
@@ -14614,6 +14636,8 @@ static int intel_atomic_commit(struct drm_device *dev,
        intel_shared_dpll_commit(state);
        intel_atomic_track_fbs(state);
 
+       intel_update_wm_bw_wa(state);
+
        if (intel_state->modeset) {
                memcpy(dev_priv->min_pixclk, intel_state->min_pixclk,
                       sizeof(intel_state->min_pixclk));
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index cc8fc84..fda6e1e 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -2878,11 +2878,7 @@ bool ilk_disable_lp_wm(struct drm_device *dev)
 
 #define SKL_SAGV_BLOCK_TIME    30 /* µs */
 
-/*
- * FIXME: We still don't have the proper code detect if we need to apply the 
WA,
- * so assume we'll always need it in order to avoid underruns.
- */
-static bool skl_needs_memory_bw_wa(struct intel_atomic_state *state)
+static bool intel_needs_memory_bw_wa(struct intel_atomic_state *state)
 {
        struct drm_i915_private *dev_priv = to_i915(state->base.dev);
 
@@ -3056,7 +3052,7 @@ bool intel_can_enable_sagv(struct drm_atomic_state *state)
 
                latency = dev_priv->wm.skl_latency[level];
 
-               if (skl_needs_memory_bw_wa(intel_state) &&
+               if (intel_needs_memory_bw_wa(intel_state) &&
                    plane->base.state->fb->modifier ==
                    I915_FORMAT_MOD_X_TILED)
                        latency += 15;
@@ -3584,7 +3580,7 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
        uint32_t y_min_scanlines;
        struct intel_atomic_state *state =
                to_intel_atomic_state(cstate->base.state);
-       bool apply_memory_bw_wa = skl_needs_memory_bw_wa(state);
+       enum watermark_memory_wa mem_wa;
        bool y_tiled, x_tiled;
 
        if (latency == 0 || !cstate->base.active || 
!intel_pstate->base.visible) {
@@ -3600,7 +3596,8 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
        if (IS_KABYLAKE(dev_priv) && dev_priv->ipc_enabled)
                latency += 4;
 
-       if (apply_memory_bw_wa && x_tiled)
+       mem_wa = state->wm_results.mem_wa;
+       if (mem_wa != WATERMARK_WA_NONE && x_tiled)
                latency += 15;
 
        width = drm_rect_width(&intel_pstate->base.src) >> 16;
@@ -3635,7 +3632,7 @@ static int skl_compute_plane_wm(const struct 
drm_i915_private *dev_priv,
                y_min_scanlines = 4;
        }
 
-       if (apply_memory_bw_wa)
+       if (mem_wa == WATERMARK_WA_Y_TILED)
                y_min_scanlines *= 2;
 
        plane_bytes_per_line = width * cpp;
@@ -4063,6 +4060,15 @@ skl_compute_ddb(struct drm_atomic_state *state)
        }
 
        /*
+        * If Watermark workaround is changed we need to recalculate
+        * watermark values for all active pipes
+        */
+       if (intel_state->wm_results.mem_wa != dev_priv->wm.skl_hw.mem_wa) {
+               realloc_pipes = ~0;
+               intel_state->wm_results.dirty_pipes = ~0;
+       }
+
+       /*
         * We're not recomputing for the pipes not included in the commit, so
         * make sure we start with the current state.
         */
@@ -4087,6 +4093,133 @@ skl_compute_ddb(struct drm_atomic_state *state)
        return 0;
 }
 
+static int
+skl_compute_memory_bandwidth_wm_wa(struct drm_atomic_state *state)
+{
+       struct drm_device *dev = state->dev;
+       struct drm_i915_private *dev_priv = to_i915(dev);
+       struct intel_atomic_state *intel_state = to_intel_atomic_state(state);
+       struct memdev_info *memdev_info = &dev_priv->memdev_info;
+       struct skl_wm_values *results = &intel_state->wm_results;
+       struct drm_crtc *crtc;
+       struct drm_crtc_state *cstate;
+       int active_pipes = 0;
+       uint32_t max_pipe_bw_kbps = 0, total_pipe_bw_kbps;
+       int display_bw_percentage;
+       bool y_tile_enabled = false;
+       int ret, i;
+
+       if (!intel_needs_memory_bw_wa(intel_state)) {
+               results->mem_wa = WATERMARK_WA_NONE;
+               return 0;
+       }
+
+       if (!memdev_info->valid)
+               goto exit;
+
+       ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
+                       state->acquire_ctx);
+       if (ret)
+               return ret;
+
+       memcpy(results->pipe_bw_kbps, dev_priv->wm.skl_hw.pipe_bw_kbps,
+                       sizeof(results->pipe_bw_kbps));
+       memcpy(results->pipe_ytiled, dev_priv->wm.skl_hw.pipe_ytiled,
+                       sizeof(results->pipe_ytiled));
+
+       for_each_crtc_in_state(state, crtc, cstate, i) {
+               struct drm_plane *plane;
+               const struct drm_plane_state *pstate;
+               int active_planes = 0;
+               uint32_t max_plane_bw_kbps = 0;
+
+               results->pipe_ytiled[i] = false;
+
+               if (!cstate->active) {
+                       results->pipe_bw_kbps[i] = 0;
+                       continue;
+               }
+
+               drm_atomic_crtc_state_for_each_plane_state(plane, pstate,
+                                                               cstate) {
+                       struct drm_framebuffer *fb;
+                       uint32_t plane_bw_kbps;
+                       enum plane_id id = to_intel_plane(plane)->id;
+
+                       if (!pstate->visible)
+                               continue;
+
+                       if (WARN_ON(!pstate->fb))
+                               continue;
+
+                       if (id == PLANE_CURSOR)
+                               continue;
+
+                       fb = pstate->fb;
+                       if ((fb->modifier == I915_FORMAT_MOD_Y_TILED ||
+                               fb->modifier == I915_FORMAT_MOD_Yf_TILED))
+                               results->pipe_ytiled[i] = true;
+
+                       plane_bw_kbps = skl_adjusted_plane_pixel_rate(
+                                               to_intel_crtc_state(cstate),
+                                               to_intel_plane_state(pstate));
+                       max_plane_bw_kbps = max(plane_bw_kbps,
+                                                       max_plane_bw_kbps);
+                       active_planes++;
+               }
+               results->pipe_bw_kbps[i] = max_plane_bw_kbps * active_planes;
+       }
+
+       for_each_pipe(dev_priv, i) {
+               if (results->pipe_bw_kbps[i]) {
+                       max_pipe_bw_kbps = max(max_pipe_bw_kbps,
+                                       results->pipe_bw_kbps[i]);
+                       active_pipes++;
+               }
+               if (results->pipe_ytiled[i])
+                       y_tile_enabled = true;
+       }
+
+       total_pipe_bw_kbps = max_pipe_bw_kbps * active_pipes;
+       display_bw_percentage = DIV_ROUND_UP_ULL(total_pipe_bw_kbps * 100,
+                                               memdev_info->bandwidth_kbps);
+
+       /*
+        * If there is any Ytile plane enabled and arbitrated display
+        * bandwidth > 20% of raw system memory bandwidth
+        * Enale Y-tile related WA
+        *
+        * If memory is dual channel single rank, Xtile limit = 35%, else Xtile
+        * limit = 60%
+        * If there is no Ytile plane enabled and
+        * arbitrated display bandwidth > Xtile limit
+        * Enable X-tile realated WA
+        */
+       if (y_tile_enabled && (display_bw_percentage > 20))
+               results->mem_wa = WATERMARK_WA_Y_TILED;
+       else {
+               int x_tile_percentage = 60;
+               enum rank rank = DRAM_RANK_SINGLE;
+
+               if (memdev_info->rank != DRAM_RANK_INVALID)
+                       rank = memdev_info->rank;
+
+               if ((rank == DRAM_RANK_SINGLE) &&
+                                       (memdev_info->num_channels == 2))
+                       x_tile_percentage = 35;
+
+               if (display_bw_percentage > x_tile_percentage)
+                       results->mem_wa = WATERMARK_WA_X_TILED;
+       }
+
+       return 0;
+
+exit:
+       results->mem_wa = WATERMARK_WA_Y_TILED;
+       return 0;
+}
+
+
 static void
 skl_copy_wm_for_pipe(struct skl_wm_values *dst,
                     struct skl_wm_values *src,
@@ -4162,6 +4295,10 @@ skl_compute_wm(struct drm_atomic_state *state)
        /* Clear all dirty flags */
        results->dirty_pipes = 0;
 
+       ret = skl_compute_memory_bandwidth_wm_wa(state);
+       if (ret)
+               return ret;
+
        ret = skl_compute_ddb(state);
        if (ret)
                return ret;
-- 
2.10.1

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