drm/dp_mst: Refactor drm_dp_mst_handle_down_rep()

* Remove the big ugly have_eomt conditional
* Store &mgr->down_rep_recv.initial_hdr in a var to make line wrapping
  easier
* Remove duplicate memset() calls
* Actually wrap lines

Cc: Juston Li <juston.li@intel.com>
Cc: Imre Deak <imre.deak@intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Harry Wentland <hwentlan@amd.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190903204645.25487-14-lyude@redhat.com

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -3205,68 +3205,66 @@ static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up)
 
 static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
 {
-	int ret = 0;
+	struct drm_dp_sideband_msg_tx *txmsg;
+	struct drm_dp_mst_branch *mstb;
+	struct drm_dp_sideband_msg_hdr *hdr = &mgr->down_rep_recv.initial_hdr;
+	int slot = -1;
+
+	if (!drm_dp_get_one_sb_msg(mgr, false))
+		goto clear_down_rep_recv;
 
-	if (!drm_dp_get_one_sb_msg(mgr, false)) {
-		memset(&mgr->down_rep_recv, 0,
-		       sizeof(struct drm_dp_sideband_msg_rx));
+	if (!mgr->down_rep_recv.have_eomt)
 		return 0;
+
+	mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
+	if (!mstb) {
+		DRM_DEBUG_KMS("Got MST reply from unknown device %d\n",
+			      hdr->lct);
+		goto clear_down_rep_recv;
 	}
 
-	if (mgr->down_rep_recv.have_eomt) {
-		struct drm_dp_sideband_msg_tx *txmsg;
-		struct drm_dp_mst_branch *mstb;
-		int slot = -1;
-		mstb = drm_dp_get_mst_branch_device(mgr,
-						    mgr->down_rep_recv.initial_hdr.lct,
-						    mgr->down_rep_recv.initial_hdr.rad);
+	/* find the message */
+	slot = hdr->seqno;
+	mutex_lock(&mgr->qlock);
+	txmsg = mstb->tx_slots[slot];
+	/* remove from slots */
+	mutex_unlock(&mgr->qlock);
 
-		if (!mstb) {
-			DRM_DEBUG_KMS("Got MST reply from unknown device %d\n", mgr->down_rep_recv.initial_hdr.lct);
-			memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
-			return 0;
-		}
+	if (!txmsg) {
+		DRM_DEBUG_KMS("Got MST reply with no msg %p %d %d %02x %02x\n",
+			      mstb, hdr->seqno, hdr->lct, hdr->rad[0],
+			      mgr->down_rep_recv.msg[0]);
+		goto no_msg;
+	}
 
-		/* find the message */
-		slot = mgr->down_rep_recv.initial_hdr.seqno;
-		mutex_lock(&mgr->qlock);
-		txmsg = mstb->tx_slots[slot];
-		/* remove from slots */
-		mutex_unlock(&mgr->qlock);
-
-		if (!txmsg) {
-			DRM_DEBUG_KMS("Got MST reply with no msg %p %d %d %02x %02x\n",
-			       mstb,
-			       mgr->down_rep_recv.initial_hdr.seqno,
-			       mgr->down_rep_recv.initial_hdr.lct,
-				      mgr->down_rep_recv.initial_hdr.rad[0],
-				      mgr->down_rep_recv.msg[0]);
-			drm_dp_mst_topology_put_mstb(mstb);
-			memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
-			return 0;
-		}
+	drm_dp_sideband_parse_reply(&mgr->down_rep_recv, &txmsg->reply);
 
-		drm_dp_sideband_parse_reply(&mgr->down_rep_recv, &txmsg->reply);
+	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
+		DRM_DEBUG_KMS("Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
+			      txmsg->reply.req_type,
+			      drm_dp_mst_req_type_str(txmsg->reply.req_type),
+			      txmsg->reply.u.nak.reason,
+			      drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
+			      txmsg->reply.u.nak.nak_data);
 
-		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
-			DRM_DEBUG_KMS("Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
-				      txmsg->reply.req_type,
-				      drm_dp_mst_req_type_str(txmsg->reply.req_type),
-				      txmsg->reply.u.nak.reason,
-				      drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
-				      txmsg->reply.u.nak.nak_data);
-
-		memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
-		drm_dp_mst_topology_put_mstb(mstb);
+	memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+	drm_dp_mst_topology_put_mstb(mstb);
 
-		mutex_lock(&mgr->qlock);
-		txmsg->state = DRM_DP_SIDEBAND_TX_RX;
-		mstb->tx_slots[slot] = NULL;
-		mutex_unlock(&mgr->qlock);
+	mutex_lock(&mgr->qlock);
+	txmsg->state = DRM_DP_SIDEBAND_TX_RX;
+	mstb->tx_slots[slot] = NULL;
+	mutex_unlock(&mgr->qlock);
 
-		wake_up_all(&mgr->tx_waitq);
-	}
-	return ret;
+	wake_up_all(&mgr->tx_waitq);
+
+	return 0;
+
+no_msg:
+	drm_dp_mst_topology_put_mstb(mstb);
+clear_down_rep_recv:
+	memset(&mgr->down_rep_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
+
+	return 0;
 }
 
 static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)