drm/amd/display: Fix driver load crash in amdgpu_dm

[Why]
This fixes an regression introduced by:
    drm/amd/display: add stream ID and otg instance in dc_stream_state

During driver initialization, a null pointer deref is raised. This is
caused by searching for a stream status in the dc->current_state before
the dc_state swap happens at the end of dc_commit_state_no_check().
Since the swap has not happened, the dc_state to be swapped in should
be searched, and not dc->current_state.

[How]
Add a function that searches for the stream status within the given
dc_state, instead of dc->current_state. Use that before the state swap
happens in dc_commit_state_no_check().

Also remove duplicate occurrences of this function in amdgpu_dm.c.
Signed-off-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -4458,20 +4458,6 @@ static void prepare_flip_isr(struct amdgpu_crtc *acrtc)
 						 acrtc->crtc_id);
 }
 
-struct dc_stream_status *dc_state_get_stream_status(
-	struct dc_state *state,
-	struct dc_stream_state *stream)
-{
-	uint8_t i;
-
-	for (i = 0; i < state->stream_count; i++) {
-		if (stream == state->streams[i])
-			return &state->stream_status[i];
-	}
-
-	return NULL;
-}
-
 static void update_freesync_state_on_stream(
 	struct amdgpu_display_manager *dm,
 	struct dm_crtc_state *new_crtc_state,
@@ -5079,8 +5065,8 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 					dc_stream_get_status(dm_new_crtc_state->stream);
 
 			if (!status)
-				status = dc_state_get_stream_status(dc_state,
-								    dm_new_crtc_state->stream);
+				status = dc_stream_get_status_from_state(dc_state,
+									 dm_new_crtc_state->stream);
 
 			if (!status)
 				DC_ERR("got no status for stream %p on acrtc%p\n", dm_new_crtc_state->stream, acrtc);
@@ -5844,8 +5830,8 @@ dm_determine_update_type_for_commit(struct dc *dc,
 					goto cleanup;
 				}
 
-				status = dc_state_get_stream_status(old_dm_state->context,
-								    new_dm_crtc_state->stream);
+				status = dc_stream_get_status_from_state(old_dm_state->context,
+									 new_dm_crtc_state->stream);
 
 				update_type = dc_check_update_surfaces_for_stream(dc, updates, num_plane,
 										  &stream_update, status);

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -1071,7 +1071,7 @@ static enum dc_status dc_commit_state_no_check(struct dc *dc, struct dc_state *c
 			}
 		}
 
-		status = dc_stream_get_status(context->streams[i]);
+		status = dc_stream_get_status_from_state(context, context->streams[i]);
 		context->streams[i]->out.otg_offset = status->primary_otg_inst;
 
 		CONN_MSG_MODE(link, "{%dx%d, %dx%d@%dKhz}",

drivers/gpu/drm/amd/display/dc/core/dc_stream.c

@@ -160,20 +160,42 @@ struct dc_stream_state *dc_create_stream_for_sink(
 	return stream;
 }
 
-struct dc_stream_status *dc_stream_get_status(
+/**
+ * dc_stream_get_status_from_state - Get stream status from given dc state
+ * @state: DC state to find the stream status in
+ * @stream: The stream to get the stream status for
+ *
+ * The given stream is expected to exist in the given dc state. Otherwise, NULL
+ * will be returned.
+ */
+struct dc_stream_status *dc_stream_get_status_from_state(
+	struct dc_state *state,
 	struct dc_stream_state *stream)
 {
 	uint8_t i;
-	struct dc  *dc = stream->ctx->dc;
 
-	for (i = 0; i < dc->current_state->stream_count; i++) {
-		if (stream == dc->current_state->streams[i])
-			return &dc->current_state->stream_status[i];
+	for (i = 0; i < state->stream_count; i++) {
+		if (stream == state->streams[i])
+			return &state->stream_status[i];
 	}
 
 	return NULL;
 }
 
+/**
+ * dc_stream_get_status() - Get current stream status of the given stream state
+ * @stream: The stream to get the stream status for.
+ *
+ * The given stream is expected to exist in dc->current_state. Otherwise, NULL
+ * will be returned.
+ */
+struct dc_stream_status *dc_stream_get_status(
+	struct dc_stream_state *stream)
+{
+	struct dc *dc = stream->ctx->dc;
+	return dc_stream_get_status_from_state(dc->current_state, stream);
+}
+
 /**
  * dc_stream_set_cursor_attributes() - Update cursor attributes and set cursor surface address
  */

drivers/gpu/drm/amd/display/dc/dc_stream.h

@@ -278,6 +278,9 @@ void update_stream_signal(struct dc_stream_state *stream, struct dc_sink *sink);
 void dc_stream_retain(struct dc_stream_state *dc_stream);
 void dc_stream_release(struct dc_stream_state *dc_stream);
 
+struct dc_stream_status *dc_stream_get_status_from_state(
+	struct dc_state *state,
+	struct dc_stream_state *stream);
 struct dc_stream_status *dc_stream_get_status(
 	struct dc_stream_state *dc_stream);