drm/i915: Precompute can_sagv for each wm level

In order to remove intel_atomic_crtc_state_for_each_plane_state()
from skl_crtc_can_enable_sagv() we can simply precompute whether
each wm level can tolerate the SAGV block time latency or not.

This has the nice side benefit that we remove the duplicated
wm level latency calculation. In fact the copy of that code
we had in skl_crtc_can_enable_sagv() didn't even handle
WaIncreaseLatencyIPCEnabled/Display WA #1141 whereas the copy
in skl_compute_plane_wm() did. So now we just have the one
copy which handles all the w/as.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20201106173042.7534-5-ville.syrjala@linux.intel.com
Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>

drivers/gpu/drm/i915/display/intel_display_types.h

@@ -686,6 +686,7 @@ struct skl_wm_level {
 	u8 plane_res_l;
 	bool plane_en;
 	bool ignore_lines;
+	bool can_sagv;
 };
 
 struct skl_plane_wm {

drivers/gpu/drm/i915/intel_pm.c

@@ -3873,9 +3873,7 @@ static bool skl_crtc_can_enable_sagv(const struct intel_crtc_state *crtc_state)
 {
 	struct intel_crtc *crtc = to_intel_crtc(crtc_state->uapi.crtc);
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
-	struct intel_plane *plane;
-	const struct intel_plane_state *plane_state;
-	int level, latency;
+	enum plane_id plane_id;
 
 	if (!intel_has_sagv(dev_priv))
 		return false;
@@ -3886,9 +3884,10 @@ static bool skl_crtc_can_enable_sagv(const struct intel_crtc_state *crtc_state)
 	if (crtc_state->hw.pipe_mode.flags & DRM_MODE_FLAG_INTERLACE)
 		return false;
 
-	intel_atomic_crtc_state_for_each_plane_state(plane, plane_state, crtc_state) {
+	for_each_plane_id_on_crtc(crtc, plane_id) {
 		const struct skl_plane_wm *wm =
-			&crtc_state->wm.skl.optimal.planes[plane->id];
+			&crtc_state->wm.skl.optimal.planes[plane_id];
+		int level;
 
 		/* Skip this plane if it's not enabled */
 		if (!wm->wm[0].plane_en)
@@ -3899,19 +3898,12 @@ static bool skl_crtc_can_enable_sagv(const struct intel_crtc_state *crtc_state)
 		     !wm->wm[level].plane_en; --level)
 		     { }
 
-		latency = dev_priv->wm.skl_latency[level];
-
-		if (skl_needs_memory_bw_wa(dev_priv) &&
-		    plane_state->uapi.fb->modifier ==
-		    I915_FORMAT_MOD_X_TILED)
-			latency += 15;
-
 		/*
 		 * 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)
+		if (!wm->wm[level].can_sagv)
 			return false;
 	}
 
@@ -5375,6 +5367,9 @@ static void skl_compute_plane_wm(const struct intel_crtc_state *crtc_state,
 	/* Bspec says: value >= plane ddb allocation -> invalid, hence the +1 here */
 	result->min_ddb_alloc = max(min_ddb_alloc, res_blocks) + 1;
 	result->plane_en = true;
+
+	if (INTEL_GEN(dev_priv) < 12)
+		result->can_sagv = latency >= dev_priv->sagv_block_time_us;
 }
 
 static void