drm/i915: Add debugs for mbus joining and dbuf ratio programming

Add some debugs so that we can actually observe what is
actually happening during the mbus/dbuf programming steps.
We can just shove them into fairly low level functions as
none of them are called during any critical sections/etc.
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Reviewed-by: Gustavo Sousa <gustavo.sousa@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240402155016.13733-10-ville.syrjala@linux.intel.com

drivers/gpu/drm/i915/display/skl_watermark.c

@@ -3647,6 +3647,9 @@ void intel_dbuf_mdclk_cdclk_ratio_update(struct drm_i915_private *i915, u8 ratio
 	if (joined_mbus)
 		ratio *= 2;
 
+	drm_dbg_kms(&i915->drm, "Updating dbuf ratio to %d (mbus joined: %s)\n",
+		    ratio, str_yes_no(joined_mbus));
+
 	for_each_dbuf_slice(i915, slice)
 		intel_de_rmw(i915, DBUF_CTL_S(slice),
 			     DBUF_MIN_TRACKER_STATE_SERVICE_MASK,
@@ -3680,10 +3683,16 @@ static void intel_dbuf_mdclk_min_tracker_update(struct intel_atomic_state *state
 static void intel_dbuf_mbus_join_update(struct intel_atomic_state *state)
 {
 	struct drm_i915_private *i915 = to_i915(state->base.dev);
+	const struct intel_dbuf_state *old_dbuf_state =
+		intel_atomic_get_old_dbuf_state(state);
 	const struct intel_dbuf_state *new_dbuf_state =
 		intel_atomic_get_new_dbuf_state(state);
 	u32 mbus_ctl;
 
+	drm_dbg_kms(&i915->drm, "Changing mbus joined: %s -> %s\n",
+		    str_yes_no(old_dbuf_state->joined_mbus),
+		    str_yes_no(new_dbuf_state->joined_mbus));
+
 	/*
 	 * TODO: Implement vblank synchronized MBUS joining changes.
 	 * Must be properly coordinated with dbuf reprogramming.