pmdomain: apple: pmc: enable the M4 external display boost, for 4K at 120 Hz

Documentation/devicetree/bindings/power/apple,pmc.yaml

@@ -35,8 +35,10 @@ properties:
     description: |
       The perf-state floor words of the voter agents ("voters"), and the
       per-agent words holding the floor the PMC honours for each agent with
-      the per-rail interface enable words ("rails"). Optionally, the cluster
-      enable control word followed by its status word ("clusters").
+      the per-rail interface enable words ("rails"); on T8132 the rails
+      block also holds the bandwidth request and boost interface enable
+      words. Optionally, the cluster enable control word followed by its
+      status word ("clusters").
 
   reg-names:
     description: |
@@ -178,6 +180,43 @@ patternProperties:
       - '#power-domain-cells'
       - apple,cluster-bit
 
+  '^interface-[a-z0-9-]+$':
+    type: object
+    description: |
+      A display pipe's interface enables, provided as a power domain. The
+      bandwidth request (BWR) and boost interfaces each have an enable word
+      with one bit per agent, and the PMC ignores the pipe's bandwidth and
+      boost votes while its bits are clear. Both bits are set after the
+      parent domain powers on, and cleared before it powers off.
+    additionalProperties: false
+
+    properties:
+      label:
+        description: Name of the power domain.
+
+      '#power-domain-cells':
+        const: 0
+
+      power-domains:
+        maxItems: 1
+        description: Domain that must be powered while the enables are set.
+
+      apple,bwr-bit:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        maximum: 31
+        description: Bit of the pipe in the BWR interface enable word.
+
+      apple,boost-bit:
+        $ref: /schemas/types.yaml#/definitions/uint32
+        maximum: 31
+        description: Bit of the pipe in the boost interface enable word.
+
+    required:
+      - '#power-domain-cells'
+      - power-domains
+      - apple,bwr-bit
+      - apple,boost-bit
+
   '^performance-controller@[0-9a-f]+$':
     type: object
     description: The host performance controller's voter agent.
@@ -207,6 +246,17 @@ required:
   - reg
   - reg-names
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          not:
+            contains:
+              const: apple,t8132-pmc
+    then:
+      patternProperties:
+        '^interface-[a-z0-9-]+$': false
+
 additionalProperties: false
 
 examples:
@@ -245,3 +295,27 @@ examples:
             };
         };
     };
+
+  - |
+    soc {
+        #address-cells = <2>;
+        #size-cells = <2>;
+
+        power-management@382800000 {
+            compatible = "apple,t8132-pmc";
+            reg = <0x3 0x82800000 0x0 0x10000>,
+                  <0x3 0x828aa000 0x0 0x3000>;
+            reg-names = "voters", "rails";
+            #address-cells = <1>;
+            #size-cells = <0>;
+            apple,static-voters = <3>;
+
+            interface-dispext0 {
+                label = "dispext0-interface";
+                #power-domain-cells = <0>;
+                power-domains = <&ps_dispext0_sys>;
+                apple,bwr-bit = <3>;
+                apple,boost-bit = <1>;
+            };
+        };
+    };

arch/arm64/boot/dts/apple/t8132-j713.dts

@@ -540,6 +540,18 @@
 	apple,static-voters = <3>;
 };
 
+/*
+ * The PMC enables of an external pipe are set once the pipe's SYS state is
+ * on, and before its FE state powers on.
+ */
+&ps_dispext0_fe {
+	power-domains = <&ps_dispext0_sys>, <&pmc_dispext0>;
+};
+
+&ps_dispext1_fe {
+	power-domains = <&ps_dispext1_sys>, <&pmc_dispext1>;
+};
+
 &smc {
 	status = "okay";
 

arch/arm64/boot/dts/apple/t8132-memory.dtsi

@@ -19,6 +19,27 @@
 		apple,pmp = <&pmp>;
 		status = "disabled";
 
+		/*
+		 * The external display pipes' bandwidth request (BWR) and
+		 * boost interface enables. The PMC ignores a pipe's bandwidth
+		 * and display clock votes while they are clear.
+		 */
+		pmc_dispext0: interface-dispext0 {
+			label = "dispext0-interface";
+			#power-domain-cells = <0>;
+			power-domains = <&ps_dispext0_sys>;
+			apple,bwr-bit = <3>;
+			apple,boost-bit = <1>;
+		};
+
+		pmc_dispext1: interface-dispext1 {
+			label = "dispext1-interface";
+			#power-domain-cells = <0>;
+			power-domains = <&ps_dispext1_sys>;
+			apple,bwr-bit = <4>;
+			apple,boost-bit = <2>;
+		};
+
 		clpc: performance-controller@3 {
 			compatible = "apple,t8132-clpc";
 			reg = <3>;

drivers/pmdomain/apple/Kconfig

@@ -74,8 +74,9 @@ config APPLE_PMC
 	  shared rails, such as the DRAM controller and the SoC fabric,
 	  between voter agents. This driver enables the static agents and
 	  provides power domains that enable a dynamic agent, such as the
-	  GPU, while its device is powered on. It can also limit the DRAM
-	  controller rail as a thermal cooling device.
+	  GPU, or a display pipe's bandwidth and boost interfaces, while
+	  its device is powered on. It can also limit the DRAM controller
+	  rail as a thermal cooling device.
 
 config APPLE_PMC_KUNIT_TEST
 	bool "KUnit tests for the Apple PMC voter interface" if !KUNIT_ALL_TESTS

drivers/pmdomain/apple/pmc-test.c

@@ -8,6 +8,7 @@
 
 #include <kunit/device.h>
 #include <kunit/test.h>
+#include <linux/pm_runtime.h>
 
 #define APPLE_PMC_TEST_RAILS_SIZE	0x4000
 
@@ -281,6 +282,209 @@ static void apple_pmc_test_dcs_floor(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, apple_pmc_test_ap_floor(pmc) & ~APPLE_PMC_RAIL_MASK(hw->dcs_rail), 0U);
 }
 
+/*
+ * A T8132 interface domain sets and clears its own BWR and boost enables
+ * only: the internal display's boost enable, bit 0, stays set.
+ */
+static void apple_pmc_test_interface(struct kunit *test)
+{
+	struct apple_pmc *pmc = apple_pmc_test_alloc(test);
+	struct apple_pmc_domain dom = {
+		.pmc = pmc, .interface = true, .bwr_bit = 3, .boost_bit = 1,
+	};
+	const struct apple_pmc_hw *hw = &apple_pmc_hw_t8132;
+
+	pmc->hw = hw;
+	writel(BIT(0), pmc->rails + hw->boost_enable);
+
+	KUNIT_ASSERT_EQ(test, apple_pmc_domain_power_on(&dom.genpd), 0);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->bwr_enable), BIT(3));
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->boost_enable), BIT(0) | BIT(1));
+	KUNIT_ASSERT_EQ(test, apple_pmc_domain_power_off(&dom.genpd), 0);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->bwr_enable), 0U);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->boost_enable), BIT(0));
+}
+
+struct apple_pmc_test_stuck {
+	u32 offset;
+	u32 value;
+};
+
+/* The interface enable word at stuck->offset keeps stuck->value. */
+static u32 apple_pmc_test_stuck_read(struct apple_pmc *pmc, u32 offset)
+{
+	struct kunit *test = kunit_get_current_test();
+	struct apple_pmc_test_stuck *stuck = test->priv;
+
+	if (offset == stuck->offset)
+		writel(stuck->value, pmc->rails + offset);
+	return readl(pmc->rails + offset);
+}
+
+/*
+ * If the BWR enable does not change, the boost enable goes back too, both
+ * when the domain powers on and when it powers off.
+ */
+static void apple_pmc_test_interface_stuck(struct kunit *test)
+{
+	struct apple_pmc *pmc = apple_pmc_test_alloc(test);
+	struct apple_pmc_domain dom = {
+		.pmc = pmc, .interface = true, .bwr_bit = 3, .boost_bit = 1,
+	};
+	const struct apple_pmc_hw *hw = &apple_pmc_hw_t8132;
+	struct apple_pmc_test_stuck stuck = { .offset = hw->bwr_enable };
+
+	pmc->hw = hw;
+	writel(BIT(0), pmc->rails + hw->boost_enable);
+	test->priv = &stuck;
+	kunit_activate_static_stub(test, apple_pmc_interface_read,
+				   apple_pmc_test_stuck_read);
+
+	KUNIT_EXPECT_EQ(test, apple_pmc_domain_power_on(&dom.genpd), -EIO);
+	KUNIT_EXPECT_EQ(test, apple_pmc_interface_read(pmc, hw->bwr_enable), 0U);
+	KUNIT_EXPECT_EQ(test, apple_pmc_interface_read(pmc, hw->boost_enable), BIT(0));
+
+	stuck.value = BIT(3);
+	writel(BIT(0) | BIT(1), pmc->rails + hw->boost_enable);
+	KUNIT_EXPECT_EQ(test, apple_pmc_domain_power_off(&dom.genpd), -EIO);
+	KUNIT_EXPECT_EQ(test, apple_pmc_interface_read(pmc, hw->bwr_enable), BIT(3));
+	KUNIT_EXPECT_EQ(test, apple_pmc_interface_read(pmc, hw->boost_enable),
+			BIT(0) | BIT(1));
+
+	kunit_deactivate_static_stub(test, apple_pmc_interface_read);
+	test->priv = NULL;
+}
+
+static void apple_pmc_test_genpd_remove(void *genpd)
+{
+	pm_genpd_remove(genpd);
+}
+
+static void apple_pmc_test_genpd_detach(void *dev)
+{
+	pm_runtime_disable(dev);
+	pm_genpd_remove_device(dev);
+}
+
+/* A genpd that is removed again when the test ends, children first. */
+static struct generic_pm_domain *apple_pmc_test_genpd(struct kunit *test,
+						      struct generic_pm_domain *genpd,
+						      int ret)
+{
+	KUNIT_ASSERT_EQ(test, ret, 0);
+	KUNIT_ASSERT_EQ(test, kunit_add_action_or_reset(test,
+							apple_pmc_test_genpd_remove,
+							genpd), 0);
+	return genpd;
+}
+
+static struct apple_pmc_domain *apple_pmc_test_interface_dom(struct kunit *test,
+							     struct apple_pmc *pmc,
+							     const char *name)
+{
+	struct apple_pmc_domain *dom = kunit_kzalloc(test, sizeof(*dom), GFP_KERNEL);
+
+	KUNIT_ASSERT_NOT_NULL(test, dom);
+	dom->pmc = pmc;
+	dom->interface = true;
+	dom->bwr_bit = 3;
+	dom->boost_bit = 1;
+	dom->genpd.name = name;
+	apple_pmc_test_genpd(test, &dom->genpd, apple_pmc_interface_init(pmc, dom));
+	return dom;
+}
+
+/*
+ * Link the interface domain as the PMGR driver does: under a SYS power
+ * state, with an FE power state below both, all of them IRQ safe. Powering
+ * FE through a device sets the enables after SYS is on, and powering it
+ * off clears them.
+ */
+static void apple_pmc_test_interface_genpd(struct kunit *test)
+{
+	struct apple_pmc *pmc = apple_pmc_test_alloc(test);
+	const struct apple_pmc_hw *hw = &apple_pmc_hw_t8132;
+	struct generic_pm_domain *sys, *fe;
+	struct apple_pmc_domain *dom;
+	struct device *dev;
+
+	pmc->hw = hw;
+	writel(BIT(0), pmc->rails + hw->boost_enable);
+	pmc->saved_boost = BIT(0);
+	dev = kunit_device_register(test, "apple-pmc-test-fe");
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, dev);
+
+	sys = kunit_kzalloc(test, sizeof(*sys), GFP_KERNEL);
+	fe = kunit_kzalloc(test, sizeof(*fe), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_NULL(test, sys);
+	KUNIT_ASSERT_NOT_NULL(test, fe);
+	sys->name = "apple-pmc-test-sys";
+	sys->flags = GENPD_FLAG_IRQ_SAFE;
+	fe->name = "apple-pmc-test-fe";
+	fe->flags = GENPD_FLAG_IRQ_SAFE;
+	apple_pmc_test_genpd(test, sys, pm_genpd_init(sys, NULL, false));
+	dom = apple_pmc_test_interface_dom(test, pmc, "apple-pmc-test-interface");
+	KUNIT_EXPECT_EQ(test, dom->genpd.status, GENPD_STATE_OFF);
+	apple_pmc_test_genpd(test, fe, pm_genpd_init(fe, NULL, true));
+
+	KUNIT_ASSERT_EQ(test, pm_genpd_add_subdomain(sys, &dom->genpd), 0);
+	KUNIT_ASSERT_EQ(test, pm_genpd_add_subdomain(sys, fe), 0);
+	KUNIT_ASSERT_EQ(test, pm_genpd_add_subdomain(&dom->genpd, fe), 0);
+
+	KUNIT_ASSERT_EQ(test, pm_genpd_add_device(fe, dev), 0);
+	pm_runtime_enable(dev);
+	KUNIT_ASSERT_EQ(test, kunit_add_action_or_reset(test,
+							apple_pmc_test_genpd_detach,
+							dev), 0);
+
+	KUNIT_ASSERT_EQ(test, pm_runtime_resume_and_get(dev), 0);
+	KUNIT_EXPECT_EQ(test, dom->genpd.status, GENPD_STATE_ON);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->bwr_enable), BIT(3));
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->boost_enable), BIT(0) | BIT(1));
+
+	KUNIT_EXPECT_EQ(test, pm_runtime_put_sync_suspend(dev), 0);
+	KUNIT_EXPECT_EQ(test, dom->genpd.status, GENPD_STATE_OFF);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->bwr_enable), 0U);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->boost_enable), BIT(0));
+}
+
+/*
+ * A pipe with both enables set at boot starts on. One with only its boost
+ * enable set starts off, and a power on that fails on the BWR enable keeps
+ * that boost enable instead of clearing it.
+ */
+static void apple_pmc_test_interface_boot_state(struct kunit *test)
+{
+	struct apple_pmc *pmc = apple_pmc_test_alloc(test);
+	const struct apple_pmc_hw *hw = &apple_pmc_hw_t8132;
+	struct apple_pmc_test_stuck stuck = { .offset = hw->bwr_enable };
+	struct apple_pmc_domain *dom;
+
+	pmc->hw = hw;
+	pmc->saved_bwr = BIT(3);
+	pmc->saved_boost = BIT(0) | BIT(1);
+	dom = apple_pmc_test_interface_dom(test, pmc, "apple-pmc-test-on");
+	KUNIT_EXPECT_EQ(test, dom->genpd.status, GENPD_STATE_ON);
+
+	pmc->saved_bwr = 0;
+	writel(BIT(0) | BIT(1), pmc->rails + hw->boost_enable);
+	dom = apple_pmc_test_interface_dom(test, pmc, "apple-pmc-test-mixed");
+	KUNIT_EXPECT_EQ(test, dom->genpd.status, GENPD_STATE_OFF);
+
+	test->priv = &stuck;
+	kunit_activate_static_stub(test, apple_pmc_interface_read,
+				   apple_pmc_test_stuck_read);
+	KUNIT_EXPECT_EQ(test, apple_pmc_domain_power_on(&dom->genpd), -EIO);
+	KUNIT_EXPECT_EQ(test, apple_pmc_interface_read(pmc, hw->boost_enable),
+			BIT(0) | BIT(1));
+	kunit_deactivate_static_stub(test, apple_pmc_interface_read);
+	test->priv = NULL;
+
+	KUNIT_EXPECT_EQ(test, apple_pmc_domain_power_on(&dom->genpd), 0);
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->bwr_enable), BIT(3));
+	KUNIT_EXPECT_EQ(test, readl(pmc->rails + hw->boost_enable), BIT(0) | BIT(1));
+}
+
 static struct kunit_case apple_pmc_test_cases[] = {
 	KUNIT_CASE(apple_pmc_test_dcs_floor),
 	KUNIT_CASE(apple_pmc_test_partial_enable),
@@ -291,6 +495,10 @@ static struct kunit_case apple_pmc_test_cases[] = {
 	KUNIT_CASE(apple_pmc_test_dcs_limit_restores_ap_vote),
 	KUNIT_CASE(apple_pmc_test_floor_aggregate),
 	KUNIT_CASE(apple_pmc_test_floor_pending_timeout),
+	KUNIT_CASE(apple_pmc_test_interface),
+	KUNIT_CASE(apple_pmc_test_interface_stuck),
+	KUNIT_CASE(apple_pmc_test_interface_genpd),
+	KUNIT_CASE(apple_pmc_test_interface_boot_state),
 	{}
 };