drm/i915: Don't pin LRC in GGTT when dumping in debugfs

LRC object does not need to be mapped into the GGTT when dumping. A side-effect
of this patch is that a compiler warning goes away (not checking return value
of i915_gem_obj_ggtt_pin).

v2: Broke out individual context dumping into a new function as the indentation
was getting a bit crazy.  Added notification of contexts with no gem object for
debugging purposes.  Removed unnecessary pin_pages and unpin_pages, replaced
with explicit get_pages for the context object as there may be no backing store
allocated at this time (Comment for get_pages says "Ensure that the associated
pages are gathered from the backing storage and pinned into our object").
Improved error checking - get_pages and get_page are checked for failure.

Signed-off-by: Thomas Daniel <thomas.daniel@intel.com>
[danvet: Align paramter continuation lines properly. Also add some
braces to the nested loops again for readability.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_debugfs.c

@@ -1772,6 +1772,50 @@ static int i915_context_status(struct seq_file *m, void *unused)
 	return 0;
 }
 
+static void i915_dump_lrc_obj(struct seq_file *m,
+			      struct intel_engine_cs *ring,
+			      struct drm_i915_gem_object *ctx_obj)
+{
+	struct page *page;
+	uint32_t *reg_state;
+	int j;
+	unsigned long ggtt_offset = 0;
+
+	if (ctx_obj == NULL) {
+		seq_printf(m, "Context on %s with no gem object\n",
+			   ring->name);
+		return;
+	}
+
+	seq_printf(m, "CONTEXT: %s %u\n", ring->name,
+		   intel_execlists_ctx_id(ctx_obj));
+
+	if (!i915_gem_obj_ggtt_bound(ctx_obj))
+		seq_puts(m, "\tNot bound in GGTT\n");
+	else
+		ggtt_offset = i915_gem_obj_ggtt_offset(ctx_obj);
+
+	if (i915_gem_object_get_pages(ctx_obj)) {
+		seq_puts(m, "\tFailed to get pages for context object\n");
+		return;
+	}
+
+	page = i915_gem_object_get_page(ctx_obj, 1);
+	if (!WARN_ON(page == NULL)) {
+		reg_state = kmap_atomic(page);
+
+		for (j = 0; j < 0x600 / sizeof(u32) / 4; j += 4) {
+			seq_printf(m, "\t[0x%08lx] 0x%08x 0x%08x 0x%08x 0x%08x\n",
+				   ggtt_offset + 4096 + (j * 4),
+				   reg_state[j], reg_state[j + 1],
+				   reg_state[j + 2], reg_state[j + 3]);
+		}
+		kunmap_atomic(reg_state);
+	}
+
+	seq_putc(m, '\n');
+}
+
 static int i915_dump_lrc(struct seq_file *m, void *unused)
 {
 	struct drm_info_node *node = (struct drm_info_node *) m->private;
@@ -1792,37 +1836,9 @@ static int i915_dump_lrc(struct seq_file *m, void *unused)
 
 	list_for_each_entry(ctx, &dev_priv->context_list, link) {
 		for_each_ring(ring, dev_priv, i) {
-			struct drm_i915_gem_object *ctx_obj = ctx->engine[i].state;
-
-			if (ring->default_context == ctx)
-				continue;
-
-			if (ctx_obj) {
-				struct page *page;
-				uint32_t *reg_state;
-				int j;
-
-				i915_gem_obj_ggtt_pin(ctx_obj,
-						GEN8_LR_CONTEXT_ALIGN, 0);
-
-				page = i915_gem_object_get_page(ctx_obj, 1);
-				reg_state = kmap_atomic(page);
-
-				seq_printf(m, "CONTEXT: %s %u\n", ring->name,
-						intel_execlists_ctx_id(ctx_obj));
-
-				for (j = 0; j < 0x600 / sizeof(u32) / 4; j += 4) {
-					seq_printf(m, "\t[0x%08lx] 0x%08x 0x%08x 0x%08x 0x%08x\n",
-					i915_gem_obj_ggtt_offset(ctx_obj) + 4096 + (j * 4),
-					reg_state[j], reg_state[j + 1],
-					reg_state[j + 2], reg_state[j + 3]);
-				}
-				kunmap_atomic(reg_state);
-
-				i915_gem_object_ggtt_unpin(ctx_obj);
-
-				seq_putc(m, '\n');
-			}
+			if (ring->default_context != ctx)
+				i915_dump_lrc_obj(m, ring,
+						  ctx->engine[i].state);
 		}
 	}