[PATCH 14/19] thunderbolt: Add QUIRK_NO_USB3_BW_ALLOC

@@ -169,6 +169,7 @@ struct tb_nhi_ops {
 #define QUIRK_E2E					BIT(1)
 #define QUIRK_RESET_DMA_ON_TEARDOWN			BIT(2)
 #define QUIRK_NO_DMA_PORT				BIT(3)
+#define QUIRK_NO_USB3_BW_ALLOC				BIT(4)
 
 /*
  * Minimal number of vectors when we use MSI-X. Two for control channel

@@ -3044,6 +3044,14 @@ static int tb_start(struct tb *tb, bool reset)
 	 */
 	tb->root_switch->no_dma_port = tb->nhi->quirks & QUIRK_NO_DMA_PORT;
 
+	/*
+	 * Apple Silicon host routers do not implement the USB3 bandwidth
+	 * allocation registers: the CMR/HCA handshake is never acked and
+	 * times out. Bandwidth for USB3 tunnels is only booked in software
+	 * on these machines.
+	 */
+	tb->root_switch->no_usb3_bw_alloc = tb->nhi->quirks & QUIRK_NO_USB3_BW_ALLOC;
+
 	ret = tb_switch_configure(tb->root_switch);
 	if (ret) {
 		tb_switch_put(tb->root_switch);

@@ -140,6 +140,8 @@ struct tb_switch_tmu {
  * @nvm: Pointer to the NVM if the switch has one (%NULL otherwise)
  * @no_nvm_upgrade: Prevent NVM upgrade of this switch
  * @no_dma_port: Prevent adding the DMA port of this switch
+ * @no_usb3_bw_alloc: Host router does not implement the USB3 bandwidth
+ *		      allocation registers (ADP_USB3_CS_1..4)
  * @safe_mode: The switch is in safe-mode
  * @boot: Whether the switch was already authorized on boot or not
  * @rpm: The switch supports runtime PM

@@ -196,6 +198,7 @@ struct tb_switch {
 	struct tb_nvm *nvm;
 	bool no_nvm_upgrade;
 	bool no_dma_port;
+	bool no_usb3_bw_alloc;
 	bool safe_mode;
 	bool boot;
 	bool rpm;

@@ -2268,24 +2268,40 @@ struct tb_tunnel *tb_tunnel_discover_usb3(struct tb *tb, struct tb_port *down,
 	if (!tb_route(down->sw)) {
 		int ret;
 
-		/*
-		 * Read the initial bandwidth allocation for the first
-		 * hop tunnel.
-		 */
-		ret = usb4_usb3_port_allocated_bandwidth(down,
-			&tunnel->allocated_up, &tunnel->allocated_down);
-		if (ret)
-			goto err_deactivate;
+		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
+
+		if (down->sw->no_usb3_bw_alloc) {
+			/*
+			 * The host router does not implement the bandwidth
+			 * allocation registers and nothing can be read back
+			 * here. Book 90% of the maximum link rate in software
+			 * instead.
+			 */
+			ret = tb_usb3_max_link_rate(tunnel->dst_port, down);
+			if (ret < 0)
+				goto err_deactivate;
+
+			tunnel->allocated_up = ret * 90 / 100;
+			tunnel->allocated_down = tunnel->allocated_up;
+		} else {
+			/*
+			 * Read the initial bandwidth allocation for the first
+			 * hop tunnel.
+			 */
+			ret = usb4_usb3_port_allocated_bandwidth(down,
+				&tunnel->allocated_up, &tunnel->allocated_down);
+			if (ret)
+				goto err_deactivate;
+
+			tunnel->pre_activate = tb_usb3_pre_activate;
+			tunnel->release_unused_bandwidth =
+				tb_usb3_release_unused_bandwidth;
+			tunnel->reclaim_available_bandwidth =
+				tb_usb3_reclaim_available_bandwidth;
+		}
 
 		tb_tunnel_dbg(tunnel, "currently allocated bandwidth %d/%d Mb/s\n",
 			      tunnel->allocated_up, tunnel->allocated_down);
-
-		tunnel->pre_activate = tb_usb3_pre_activate;
-		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
-		tunnel->release_unused_bandwidth =
-			tb_usb3_release_unused_bandwidth;
-		tunnel->reclaim_available_bandwidth =
-			tb_usb3_reclaim_available_bandwidth;
 	}
 
 	tb_tunnel_dbg(tunnel, "discovered\n");

@@ -2365,12 +2381,15 @@ struct tb_tunnel *tb_tunnel_alloc_usb3(struct tb *tb, struct tb_port *up,
 		tunnel->allocated_up = min(max_rate, max_up);
 		tunnel->allocated_down = min(max_rate, max_down);
 
-		tunnel->pre_activate = tb_usb3_pre_activate;
 		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
-		tunnel->release_unused_bandwidth =
-			tb_usb3_release_unused_bandwidth;
-		tunnel->reclaim_available_bandwidth =
-			tb_usb3_reclaim_available_bandwidth;
+
+		if (!down->sw->no_usb3_bw_alloc) {
+			tunnel->pre_activate = tb_usb3_pre_activate;
+			tunnel->release_unused_bandwidth =
+				tb_usb3_release_unused_bandwidth;
+			tunnel->reclaim_available_bandwidth =
+				tb_usb3_reclaim_available_bandwidth;
+		}
 	}
 
 	return tunnel;