drm/i915/dsb: Dump the DSB command buffer when DSB fails

Dump the full DSB command buffers and head/tail pointers if the
the DSB hasn't completed its job in time.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230606191504.18099-4-ville.syrjala@linux.intel.comReviewed-by: Animesh Manna <animesh.manna@intel.com>

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

@@ -93,6 +93,22 @@ static bool assert_dsb_has_room(struct intel_dsb *dsb)
 			 crtc->base.base.id, crtc->base.name, dsb->id);
 }
 
+static void intel_dsb_dump(struct intel_dsb *dsb)
+{
+	struct intel_crtc *crtc = dsb->crtc;
+	struct drm_i915_private *i915 = to_i915(crtc->base.dev);
+	const u32 *buf = dsb->cmd_buf;
+	int i;
+
+	drm_dbg_kms(&i915->drm, "[CRTC:%d:%s] DSB %d commands {\n",
+		    crtc->base.base.id, crtc->base.name, dsb->id);
+	for (i = 0; i < ALIGN(dsb->free_pos, 64 / 4); i += 4)
+		drm_dbg_kms(&i915->drm,
+			    " 0x%08x: 0x%08x 0x%08x 0x%08x 0x%08x\n",
+			    i * 4, buf[i], buf[i+1], buf[i+2], buf[i+3]);
+	drm_dbg_kms(&i915->drm, "}\n");
+}
+
 static bool is_dsb_busy(struct drm_i915_private *i915, enum pipe pipe,
 			enum dsb_id id)
 {
@@ -258,10 +274,21 @@ void intel_dsb_wait(struct intel_dsb *dsb)
 	struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
 	enum pipe pipe = crtc->pipe;
 
-	if (wait_for(!is_dsb_busy(dev_priv, pipe, dsb->id), 1))
+	if (wait_for(!is_dsb_busy(dev_priv, pipe, dsb->id), 1)) {
+		u32 offset = i915_ggtt_offset(dsb->vma);
+
+		intel_de_write_fw(dev_priv, DSB_CTRL(pipe, dsb->id),
+				  DSB_ENABLE | DSB_HALT);
+
 		drm_err(&dev_priv->drm,
-			"[CRTC:%d:%s] DSB %d timed out waiting for idle\n",
-			crtc->base.base.id, crtc->base.name, dsb->id);
+			"[CRTC:%d:%s] DSB %d timed out waiting for idle (current head=0x%x, head=0x%x, tail=0x%x)\n",
+			crtc->base.base.id, crtc->base.name, dsb->id,
+			intel_de_read_fw(dev_priv, DSB_CURRENT_HEAD(pipe, dsb->id)) - offset,
+			intel_de_read_fw(dev_priv, DSB_HEAD(pipe, dsb->id)) - offset,
+			intel_de_read_fw(dev_priv, DSB_TAIL(pipe, dsb->id)) - offset);
+
+		intel_dsb_dump(dsb);
+	}
 
 	/* Attempt to reset it */
 	dsb->free_pos = 0;