thunderbolt: apple: HBR3 for a lone external monitor on the M4 (T8132), HBR2 when a second one comes

drivers/thunderbolt/apple-dpin-state.c

@@ -38,14 +38,14 @@ const struct apple_dpin_policy apple_dpin_m3 = {
  * writes only DPTX_INACTIVE (+0x0c bit 0) and polls its ACK (+0x10 bit 0),
  * gated on HPD. The DP IN interrupts are not set up (nothing handles them),
  * and a tunnel that DCP never activated is torn down without touching the
- * block at all. Both DP IN streams of an ATC PHY need one link rate, so
- * every tunnel gets HBR2 at most.
+ * block at all. Both DP IN streams of an ATC PHY need one link rate: a
+ * tunnel alone gets up to HBR3, two get HBR2 (TB_HOST_DP_SHARED_RATE).
  */
 const struct apple_dpin_policy apple_dpin_m4 = {
 	.flow = APPLE_DPIN_CHANGED,
 	.capacity_retry = true,
 	.defer_new_bringup = true,
-	.host_policy = TB_HOST_DP_NOTIFY | TB_HOST_DP_HBR2_MAX,
+	.host_policy = TB_HOST_DP_NOTIFY | TB_HOST_DP_SHARED_RATE,
 	.lazy_idle = true,
 };
 

drivers/thunderbolt/apple-dpin-test.c

@@ -381,7 +381,7 @@ static void apple_dpin_qualification_profiles(struct kunit *test)
 
 /*
  * M4 (T8132): the M3 flow without DP IN interrupts, a lazy teardown, and
- * DP tunnels capped at HBR2.
+ * DP tunnels sharing one link rate.
  */
 static void apple_dpin_m4_policy(struct kunit *test)
 {
@@ -393,15 +393,15 @@ static void apple_dpin_m4_policy(struct kunit *test)
 	KUNIT_EXPECT_FALSE(test, p->t602x_handshake);
 	KUNIT_EXPECT_TRUE(test, p->defer_new_bringup);
 	KUNIT_EXPECT_TRUE(test, p->lazy_idle);
-	KUNIT_EXPECT_EQ(test, p->host_policy, TB_HOST_DP_NOTIFY | TB_HOST_DP_HBR2_MAX);
+	KUNIT_EXPECT_EQ(test, p->host_policy, TB_HOST_DP_NOTIFY | TB_HOST_DP_SHARED_RATE);
 	/* The hooks of the M3 flow: a queue and a display pipeline both. */
 	KUNIT_EXPECT_EQ(test, apple_dpin_hooks(p, true, true), APPLE_DPIN_CHANGED);
 	KUNIT_EXPECT_EQ(test, apple_dpin_hooks(p, true, false), APPLE_DPIN_DISABLED);
 	KUNIT_EXPECT_EQ(test, apple_dpin_hooks(p, false, true), APPLE_DPIN_DISABLED);
-	/* No other Apple host is capped. */
-	KUNIT_EXPECT_FALSE(test, apple_dpin_m3.host_policy & TB_HOST_DP_HBR2_MAX);
-	KUNIT_EXPECT_FALSE(test, apple_dpin_m2.host_policy & TB_HOST_DP_HBR2_MAX);
-	KUNIT_EXPECT_FALSE(test, apple_dpin_m1.host_policy & TB_HOST_DP_HBR2_MAX);
+	/* No other Apple host shares one rate. */
+	KUNIT_EXPECT_FALSE(test, apple_dpin_m3.host_policy & TB_HOST_DP_SHARED_RATE);
+	KUNIT_EXPECT_FALSE(test, apple_dpin_m2.host_policy & TB_HOST_DP_SHARED_RATE);
+	KUNIT_EXPECT_FALSE(test, apple_dpin_m1.host_policy & TB_HOST_DP_SHARED_RATE);
 }
 
 static void apple_dpin_all_policy_fields(struct kunit *test)

drivers/thunderbolt/ctl.c

@@ -13,6 +13,7 @@
 #include <linux/pci.h>
 #include <linux/dmapool.h>
 #include <linux/workqueue.h>
+#include <kunit/static_stub.h>
 
 #include "ctl.h"
 
@@ -1111,8 +1112,14 @@ static int tb_cfg_get_error(struct tb_ctl *ctl, enum tb_cfg_space space,
 int tb_cfg_read(struct tb_ctl *ctl, void *buffer, u64 route, u32 port,
 		enum tb_cfg_space space, u32 offset, u32 length)
 {
-	struct tb_cfg_result res = tb_cfg_read_raw(ctl, buffer, route, port,
-			space, offset, length, ctl->timeout_msec);
+	struct tb_cfg_result res;
+
+	/* The KUnit tests read adapter registers without hardware */
+	KUNIT_STATIC_STUB_REDIRECT(tb_cfg_read, ctl, buffer, route, port, space, offset,
+				   length);
+
+	res = tb_cfg_read_raw(ctl, buffer, route, port, space, offset, length,
+			      ctl->timeout_msec);
 	switch (res.err) {
 	case 0:
 		/* Success */

drivers/thunderbolt/domain.c

@@ -927,6 +927,7 @@ int tb_domain_init(void)
 	ret = bus_register(&tb_bus_type);
 	if (ret)
 		goto err_xdomain;
+	tb_dp_pm_gate_init();
 
 	return 0;
 
@@ -941,6 +942,7 @@ int tb_domain_init(void)
 
 void tb_domain_exit(void)
 {
+	tb_dp_pm_gate_exit();
 	bus_unregister(&tb_bus_type);
 	ida_destroy(&tb_domain_ida);
 	tb_nvm_exit();

drivers/thunderbolt/nhi.h

@@ -225,11 +225,12 @@ struct tb_nhi_ops {
 #define TB_HOST_DP_ADAPTER_QUIRKS		BIT(4)
 #define TB_HOST_DP_INITIAL_BW_GRANT	BIT(5)
 /*
- * Both DP IN streams of a host PHY must run at one link rate: DP tunnels
- * from the host's DP IN adapters offer at most HBR2, at which two 4K60
- * streams still fit.
+ * Both DP IN streams of a host PHY must run at one link rate. A DP tunnel
+ * alone on the host router offers up to HBR3; when more are needed, all of
+ * them offer HBR2 at most (two 4K60 streams fit), a tunnel up above that
+ * being set up again at HBR2 first.
  */
-#define TB_HOST_DP_HBR2_MAX		BIT(6)
+#define TB_HOST_DP_SHARED_RATE		BIT(6)
 
 /*
  * Minimal number of vectors when we use MSI-X. Two for control channel