apple-sleep: don't let the debug link's cut wake the sleep (debug rig only)

drivers/input/misc/macsmc-input.c

@@ -270,10 +270,14 @@ static int macsmc_input_pm_prepare(struct device *dev)
 static void macsmc_input_pm_complete(struct device *dev)
 {
 	struct macsmc_input *smcin = dev_get_drvdata(dev);
+	u8 lid;
 
-	/* Still armed: a lid opened or a button pressed before the next .prepare wakes. */
+	/*
+	 * Still armed: a lid opened or a button pressed before the next .prepare wakes. A dark
+	 * wake with the lid already open (for the debug link's cut) has no lid to open.
+	 */
 	if (pm_dark_wake()) {
-		smcin->dark = true;
+		smcin->dark = apple_smc_read_u8(smcin->smc, SMC_KEY(MSLD), &lid) < 0 || lid;
 		return;
 	}
 	smcin->wakeup_mode = false;

drivers/mfd/macsmc-test.c

@@ -246,6 +246,30 @@ static void macsmc_sleep_order_test(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, ctx->seen[6], SMC_KEY(waka));
 }
 
+static void macsmc_test_outbox_poll(struct apple_smc *smc, const char *after,
+				    unsigned int min_ms, unsigned int quiet_ms)
+{
+}
+
+static void macsmc_sleep_warn_late_test(struct kunit *test)
+{
+	struct macsmc_test_context *ctx = test->priv;
+
+	kunit_activate_static_stub(test, apple_smc_ap_power, macsmc_test_ap_power);
+	kunit_activate_static_stub(test, apple_smc_outbox_poll, macsmc_test_outbox_poll);
+	ctx->result = 8;
+
+	/* A sleep that cuts the debug link: slpw comes at the noirq suspend, before slpa. */
+	ctx->smc.sleep_warn_late = true;
+	KUNIT_EXPECT_EQ(test, apple_smc_sleep_enter(&ctx->smc), 0);
+	KUNIT_EXPECT_FALSE(test, ctx->smc.sleep_warn_late);
+	KUNIT_EXPECT_TRUE(test, ctx->smc.sleep_warned);
+	KUNIT_ASSERT_EQ(test, ctx->seen_count, 3U);
+	KUNIT_EXPECT_EQ(test, ctx->seen[0], SMC_KEY(slpw));
+	KUNIT_EXPECT_EQ(test, ctx->seen[1], SMC_KEY(slpa));
+	KUNIT_EXPECT_EQ(test, ctx->seen[2], (u32)MACSMC_TEST_AP_IDLE);
+}
+
 static void macsmc_sleep_refused_test(struct kunit *test)
 {
 	struct macsmc_test_context *ctx = test->priv;
@@ -332,6 +356,19 @@ static void macsmc_wake_reason_test(struct kunit *test)
 	KUNIT_EXPECT_STREQ(test, names, "wifibt USB-C_plug");
 }
 
+static void macsmc_port_reasons_test(struct kunit *test)
+{
+	/* The debug link's cut: USB-C_plug, acdetach, or both. */
+	KUNIT_EXPECT_TRUE(test, apple_smc_port_reasons_only(BIT_ULL(42)));
+	KUNIT_EXPECT_TRUE(test, apple_smc_port_reasons_only(BIT_ULL(41) | BIT_ULL(42)));
+	/* Anything else, with it or alone, is a real wake. */
+	KUNIT_EXPECT_FALSE(test, apple_smc_port_reasons_only(0));
+	KUNIT_EXPECT_FALSE(test, apple_smc_port_reasons_only(BIT_ULL(42) | BIT_ULL(0)));
+	KUNIT_EXPECT_FALSE(test, apple_smc_port_reasons_only(BIT_ULL(42) | BIT_ULL(10)));
+	KUNIT_EXPECT_FALSE(test, apple_smc_port_reasons_only(BIT_ULL(23)));
+	KUNIT_EXPECT_FALSE(test, apple_smc_port_reasons_only(BIT_ULL(43)));
+}
+
 static struct kunit_case macsmc_parser_cases[] = {
 	KUNIT_CASE(macsmc_key_info_lock_test),
 	KUNIT_CASE(macsmc_key_index_test),
@@ -343,10 +380,12 @@ static struct kunit_case macsmc_parser_cases[] = {
 	KUNIT_CASE(macsmc_sram_value_test),
 	KUNIT_CASE(macsmc_key_info_test),
 	KUNIT_CASE(macsmc_sleep_order_test),
+	KUNIT_CASE(macsmc_sleep_warn_late_test),
 	KUNIT_CASE(macsmc_sleep_refused_test),
 	KUNIT_CASE(macsmc_notice_test),
 	KUNIT_CASE(macsmc_lid_wake_test),
 	KUNIT_CASE(macsmc_wake_reason_test),
+	KUNIT_CASE(macsmc_port_reasons_test),
 	{}
 };
 

drivers/mfd/macsmc.c

@@ -672,19 +672,21 @@ MODULE_DEVICE_TABLE(of, apple_smc_of_match);
  * from their letters.
  *
  * SMC.OutboxNotEmpty wakes the SoC while anything waits in the outbox. An event that arrives
- * during the sleep's entry (the lid, a key) is left there, so the sleep returns at once. The
- * debug link's cut fills it too, and the SMC counts what it reports after the notice as wake
- * reasons, so the cut comes before the notice.
+ * during the sleep's entry (the lid, a key) is left there, so the sleep returns at once.
+ *
+ * The debug link's cut, on a debug cable only, makes the SMC see a cable pulled and plugged
+ * back. With the cut after slpw, the SMC woke the AP right after the commit, for USB-C_plug
+ * or acdetach, in every such sleep (J700, 223 of 223), even with its outbox quiet for 500 ms
+ * before the notice. A sleep that cuts the link warns the SMC only after the cut.
  */
 
 /* The gaps macOS leaves before the AP idle notice and after it. */
 #define SMC_SLEEP_ARM_MS	6
 #define SMC_SLEEP_IDLE_MS	30
+/* The shortest gap macOS left between slpw and slpa, in two traced sleeps. */
+#define SMC_SLEEP_WARN_MS	770
 
-/*
- * After the debug link's cut. Its port and charger events keep coming for over a second,
- * and any that lands after the AP idle notice wakes the SoC at once.
- */
+/* After the debug link's cut. Its port and charger events keep coming for over a second. */
 #define SMC_OUTBOX_QUIET_MS	500
 #define SMC_OUTBOX_SETTLE_MS	5000
 
@@ -849,12 +851,30 @@ static void apple_smc_lid_wake(struct apple_smc *smc)
 		apple_sleep_lid_closed_wake();
 }
 
+/* Only what a cable pulled and plugged back reports: what the debug link's cut makes. */
+static bool apple_smc_port_reasons_only(u64 record)
+{
+	static const char * const names[] = { "acattach", "acdetach", "USB-C_plug" };
+	u64 port = 0;
+	int i, bit;
+
+	for (i = 0; i < ARRAY_SIZE(names); i++) {
+		bit = apple_smc_wake_reason_bit(names[i]);
+		if (bit >= 0)
+			port |= BIT_ULL(bit);
+	}
+
+	return record && !(record & ~port);
+}
+
 static void apple_smc_sleep_wake(struct apple_smc *smc)
 {
 	apple_smc_notice_on(smc);
 	apple_smc_write_mbse(smc, SMC_KEY(waka));
 	smc->sleep_warned = false;
 	apple_smc_lid_wake(smc);
+	if (apple_smc_port_reasons_only(smc->wake_record))
+		apple_sleep_debug_link_cut_wake();
 	/* A dark wake isn't one: with wakeup_count in use, it would abort the sleep after it. */
 	if (smc->wake_record && !pm_dark_wake())
 		pm_wakeup_event(smc->dev, 0);
@@ -864,7 +884,11 @@ static int apple_smc_prepare(struct device *dev)
 {
 	struct apple_smc *smc = dev_get_drvdata(dev);
 
-	if (pm_suspend_via_firmware())
+	if (!pm_suspend_via_firmware())
+		return 0;
+	if (apple_sleep_debug_link_up())
+		smc->sleep_warn_late = true;
+	else
 		apple_smc_sleep_warn(smc);
 
 	return 0;
@@ -875,19 +899,27 @@ static void apple_smc_complete(struct device *dev)
 {
 	struct apple_smc *smc = dev_get_drvdata(dev);
 
+	smc->sleep_warn_late = false;
 	if (smc->sleep_warned) {
 		apple_smc_write_mbse(smc, SMC_KEY(waka));
 		smc->sleep_warned = false;
 	}
 }
 
-/* The events go to their handlers as usual, through the RTKit worker. */
-static void apple_smc_outbox_settle(struct apple_smc *smc)
+/*
+ * For at least @min_ms, then until the outbox is quiet for @quiet_ms. The events go to their
+ * handlers as usual, through the RTKit worker.
+ */
+static void apple_smc_outbox_poll(struct apple_smc *smc, const char *after,
+				  unsigned int min_ms, unsigned int quiet_ms)
 {
 	unsigned int ms, quiet = 0, count = 0, last = 0;
 	int ret;
 
-	for (ms = 0; ms < SMC_OUTBOX_SETTLE_MS && quiet < SMC_OUTBOX_QUIET_MS; ms++) {
+	if (IS_ENABLED(CONFIG_MFD_MACSMC_KUNIT_TEST))
+		KUNIT_STATIC_STUB_REDIRECT(apple_smc_outbox_poll, smc, after, min_ms, quiet_ms);
+
+	for (ms = 0; ms < SMC_OUTBOX_SETTLE_MS && (ms < min_ms || quiet < quiet_ms); ms++) {
 		ret = apple_rtkit_poll(smc->rtk);
 		if (ret > 0) {
 			count += ret;
@@ -898,22 +930,35 @@ static void apple_smc_outbox_settle(struct apple_smc *smc)
 		}
 		usleep_range(1000, 1200);
 	}
-	dev_dbg(smc->dev, "debug link cut: %u messages, the last at %u ms, %s after %u ms\n",
-		count, last, quiet >= SMC_OUTBOX_QUIET_MS ? "quiet" : "still busy", ms);
+	/* A debug cable only. */
+	dev_info(smc->dev, "%s: %u messages in %u ms, the last at %u ms%s\n", after, count, ms,
+		 last, ms >= SMC_OUTBOX_SETTLE_MS ? ", still busy" : "");
+}
+
+/* The noirq suspend's part, polled: the cut, a late warning, the commit's notices. */
+static int apple_smc_sleep_enter(struct apple_smc *smc)
+{
+	if (apple_sleep_debug_link_cut())
+		apple_smc_outbox_poll(smc, "debug link cut", 0, SMC_OUTBOX_QUIET_MS);
+	if (smc->sleep_warn_late) {
+		smc->sleep_warn_late = false;
+		apple_smc_sleep_warn(smc);
+		apple_smc_outbox_poll(smc, "late sleep warning", SMC_SLEEP_WARN_MS, 0);
+	}
+
+	return apple_smc_sleep_commit(smc);
 }
 
 static int apple_smc_suspend_noirq(struct device *dev)
 {
 	struct apple_smc *smc = dev_get_drvdata(dev);
 	int ret;
 
-	if (!smc->sleep_warned)
+	if (!smc->sleep_warned && !smc->sleep_warn_late)
 		return 0;
 
 	apple_smc_set_polled(smc, true);
-	if (apple_sleep_debug_link_cut())
-		apple_smc_outbox_settle(smc);
-	ret = apple_smc_sleep_commit(smc);
+	ret = apple_smc_sleep_enter(smc);
 	apple_smc_set_polled(smc, false);
 
 	return ret;

drivers/soc/apple/sleep.c

@@ -1859,13 +1859,19 @@ static int sleep_hpm_wait_contract(struct apple_sleep *s)
 	return -ETIMEDOUT;
 }
 
+/* A live debug link holds the debug switch domain on. */
+static bool sleep_debug_link_up(struct apple_sleep *s)
+{
+	return s->hpm_spmi &&
+	       FIELD_GET(PS_ACTUAL, readl(s->ps_aon + s->soc->ps_aon_debug_switch));
+}
+
 /*
  * The debug link stays up with the ATC0 domains off, and it holds the debug domains
  * active, which macOS has idle. The only known way to end it is the port controller's
- * cold reset. To the SMC that's a cable pulled: it queues the port's events and records
- * them as wake reasons. So it has to come before the SMC's AP idle notice, not after, or
- * SMC.OutboxNotEmpty is up at the commit, and so does the partner's new contract.
- * tipd rearms the link after a refusal.
+ * cold reset. To the SMC that's a cable pulled: it records the port's events as wake
+ * reasons once it has been warned of the sleep, and wakes the AP right after the commit.
+ * So the SMC's driver warns it only after this. tipd rearms the link after a refusal.
  */
 static bool apple_sleep_usb_down(struct apple_sleep *s)
 {
@@ -1877,8 +1883,7 @@ static bool apple_sleep_usb_down(struct apple_sleep *s)
 		return false;
 	s->usb_down_ran = true;
 
-	if (!s->hpm_spmi ||
-	    !FIELD_GET(PS_ACTUAL, readl(s->ps_aon + s->soc->ps_aon_debug_switch)))
+	if (!sleep_debug_link_up(s))
 		return false;
 
 	dev_info(s->dev, "debug link: cutting it for the sleep\n");
@@ -1918,6 +1923,14 @@ bool apple_sleep_debug_link_cut(void)
 }
 EXPORT_SYMBOL_GPL(apple_sleep_debug_link_cut);
 
+bool apple_sleep_debug_link_up(void)
+{
+	struct apple_sleep *s = apple_sleep;
+
+	return s && !s->usb_down_ran && sleep_debug_link_up(s);
+}
+EXPORT_SYMBOL_GPL(apple_sleep_debug_link_up);
+
 /*
  * macOS takes the wake for a lid closing during the sleep as a dark one: every driver wakes,
  * the display stays off, and the root domain sleeps again as soon as it sees the lid closed.
@@ -1933,6 +1946,22 @@ void apple_sleep_lid_closed_wake(void)
 }
 EXPORT_SYMBOL_GPL(apple_sleep_lid_closed_wake);
 
+/*
+ * The SMC woke the AP for the port alone, and this sleep cut the debug link: the cut's own
+ * events. Sleep again. The link stays down until tipd rearms it at a full wake, so the next
+ * entry doesn't cut it.
+ */
+void apple_sleep_debug_link_cut_wake(void)
+{
+	struct apple_sleep *s = apple_sleep;
+
+	if (!s || !s->smc_woke_alone || !READ_ONCE(sleep_debug_link_cut))
+		return;
+	dev_info(s->dev, "debug link: its cut woke the sleep: dark wake\n");
+	pm_set_dark_wake();
+}
+EXPORT_SYMBOL_GPL(apple_sleep_debug_link_cut_wake);
+
 /*
  * The radio's link and the engine that starts it, in macOS's order, measured on one
  * sleep: the link into L2, the engine stopped, PERST# asserted, the PHY's clocks off.

drivers/usb/typec/tipd/core.c

@@ -1720,10 +1720,13 @@ static void cd321x_complete(struct tps6598x *tps)
 	}
 	if (pm_suspend_via_firmware() && device_property_read_bool(tps->dev, "apple,sleep-ssps"))
 		tps->data->switch_power_state(tps, TPS_SYSTEM_POWER_STATE_S0);
-	/* A link still down from an earlier sleep isn't cut again, so it stays pending. */
+	/*
+	 * A link still down from an earlier sleep isn't cut again, so it stays pending. A dark
+	 * wake sleeps again at once: the link stays down for it, and the full wake rearms it.
+	 */
 	if (apple_sleep_debug_link_was_cut(tps->dev))
 		cd321x->rearm_pending = true;
-	if (cd321x->rearm_pending) {
+	if (cd321x->rearm_pending && !pm_dark_wake()) {
 		cd321x->rearm_tries = 0;
 		cd321x_rearm_debug_link(cd321x);
 	}

include/linux/mfd/macsmc.h

@@ -116,6 +116,8 @@ struct apple_smc {
 	bool ap_notified;
 	/* Told of a coming sleep, and not yet of its end. */
 	bool sleep_warned;
+	/* To be told at the noirq suspend, after the debug link's cut. */
+	bool sleep_warn_late;
 	/* In a noirq phase: replies are polled for. */
 	bool polled;
 	/* MBSW at the last wake: what the SMC had woken the AP for. */

include/linux/soc/apple/sleep.h

@@ -108,13 +108,22 @@ bool apple_sleep_debug_link_cut_peek(struct device *dev);
  */
 bool apple_sleep_debug_link_cut(void);
 
+/* This sleep will end the debug link: for the SMC's driver, which warns the SMC after it. */
+bool apple_sleep_debug_link_up(void);
+
 /*
  * From the SMC's driver, in its noirq resume: the SMC woke the AP for the lid alone, and the
  * lid reads closed. If nothing else woke the SoC, the PM core goes back to sleep once every
  * device has resumed, as macOS does from a dark wake.
  */
 void apple_sleep_lid_closed_wake(void);
 
+/*
+ * From the SMC's driver, in its noirq resume: the SMC woke the AP for the port alone. If
+ * this sleep cut the debug link and nothing else woke the SoC, it's a dark wake.
+ */
+void apple_sleep_debug_link_cut_wake(void);
+
 /* The radio's host has its port back after a real sleep, so the next commit may stop it. */
 void apple_sleep_radio_port_up(void);
 
@@ -227,10 +236,19 @@ static inline bool apple_sleep_debug_link_cut(void)
 	return false;
 }
 
+static inline bool apple_sleep_debug_link_up(void)
+{
+	return false;
+}
+
 static inline void apple_sleep_lid_closed_wake(void)
 {
 }
 
+static inline void apple_sleep_debug_link_cut_wake(void)
+{
+}
+
 static inline void apple_sleep_radio_port_up(void)
 {
 }