drm/apple: drive the T6041 DCP and dcpext on firmware 27.2

drivers/gpu/drm/apple/Makefile

@@ -19,6 +19,7 @@ appledrm-y += iomfb_v14_7.o iomfb_v14_7_link.o
 appledrm-$(CONFIG_DRM_APPLE_DCP_T8132) += iomfb_m4.o t8132_ext_drm.o
 appledrm-y += iomfb_h17p.o
 appledrm-$(CONFIG_DRM_APPLE_KUNIT_TEST) += iomfb_h17p_test.o parser_test.o
+appledrm-$(CONFIG_DRM_APPLE_KUNIT_TEST) += iomfb_v27_test.o
 appledrm-$(CONFIG_DRM_APPLE_KUNIT_TEST) += iomfb_external_hdr_hints_test.o
 appledrm-$(CONFIG_DRM_APPLE_KUNIT_TEST) += apple_resume_test.o
 appledrm-$(CONFIG_DRM_APPLE_KUNIT_TEST) += apple_boot_display_test.o

drivers/gpu/drm/apple/dcp.c

@@ -437,11 +437,10 @@ bool dcp_t6041_ext_enabled(void)
 #include "dcp-peer-probe-v27.inc"
 
 /*
- * The backlight maximum of a desktop 26.x panel whose node has no
- * apple,max-brightness: the J616s panel's user-accessible SDR maximum (ADT
- * user-accessible-max-nits, 0x02580000 in 16.16).
+ * The backlight maximum of a T6041 panel whose node has no
+ * apple,max-brightness: the J616s panel's user-accessible SDR maximum.
  */
-#define DCP_DESKTOP_MAX_NITS	600
+#define DCP_T6041_MAX_NITS	600
 
 static bool dcp_desktop_external(struct apple_dcp *dcp)
 {
@@ -5293,14 +5292,45 @@ static int dcp_read_fw_version(struct device *dev, const char *name,
 	return len;
 }
 
+enum dcp_firmware_version dcp_t6041_firmware_version(const char *firmware,
+						      const char *compat)
+{
+	/* Firmware 27 is selected by its compatibility ABI, as on T6050. */
+	if (!strcmp(compat, "27.2.0"))
+		return DCP_FIRMWARE_V_27_0;
+	if (!strcmp(firmware, compat) &&
+	    (!strcmp(firmware, "26.5.2") || !strcmp(firmware, "26.6.2")))
+		return DCP_FIRMWARE_V_26_6_DESKTOP;
+	return DCP_FIRMWARE_UNKNOWN;
+}
+
+static bool dcp_v27_method_table_supported(struct device *dev,
+					    const char *compat)
+{
+	const struct dcp_method_entry *methods = iomfb_v27_methods(compat);
+	unsigned int num_missing;
+	const char *missing;
+
+	if (!methods) {
+		dev_err(dev, "DCP firmware-compat %s has no 27.x method table\n",
+			compat);
+		return false;
+	}
+	missing = iomfb_v27_missing_method(methods, &num_missing);
+	if (missing) {
+		dev_err(dev, "DCP firmware-compat %s not started: no ID known for %u methods (first: %s)\n",
+			compat, num_missing, missing);
+		return false;
+	}
+	return true;
+}
+
 static enum dcp_firmware_version dcp_check_firmware_version(struct device *dev)
 {
 	const struct apple_dcp_hw_data *hw = of_device_get_match_data(dev);
 	const struct dcp_v14_board *v14_board;
 	char compat_str[DCP_FW_VERSION_STR_LEN];
 	char fw_str[DCP_FW_VERSION_STR_LEN];
-	unsigned int num_missing;
-	const char *missing;
 	int ret;
 
 	/*
@@ -5317,18 +5347,12 @@ static enum dcp_firmware_version dcp_check_firmware_version(struct device *dev)
 
 	if (hw->firmware_compat == DCP_FIRMWARE_V_27_0) {
 		ret = dcp_read_fw_version(dev, "apple,firmware-compat", compat_str);
-		if (ret < 0 || !iomfb_v27_methods(compat_str)) {
-			dev_err(dev, "DCP firmware-compat %s has no 27.x method table\n",
-				ret < 0 ? "missing" : compat_str);
+		if (ret < 0) {
+			dev_err(dev, "DCP firmware-compat missing has no 27.x method table\n");
 			return DCP_FIRMWARE_UNKNOWN;
 		}
-		missing = iomfb_v27_missing_method(iomfb_v27_methods(compat_str),
-						   &num_missing);
-		if (missing) {
-			dev_err(dev, "DCP firmware-compat %s not started: no ID known for %u methods (first: %s)\n",
-				compat_str, num_missing, missing);
+		if (!dcp_v27_method_table_supported(dev, compat_str))
 			return DCP_FIRMWARE_UNKNOWN;
-		}
 		return DCP_FIRMWARE_V_27_0;
 	}
 
@@ -5351,11 +5375,17 @@ static enum dcp_firmware_version dcp_check_firmware_version(struct device *dev)
 	    of_device_is_compatible(dev->of_node, "apple,t6041-dcpext")) {
 		int compat_ret = dcp_read_fw_version(dev, "apple,firmware-compat",
 						     compat_str);
-
-		if (ret >= 0 && compat_ret >= 0 && !strcmp(fw_str, compat_str) &&
-		    (!strcmp(fw_str, "26.5.2") || !strcmp(fw_str, "26.6.2")))
-			return DCP_FIRMWARE_V_26_6_DESKTOP;
-		dev_err(dev, "T6041 display not started: DCP firmware %s (compat %s) is not 26.5.2 or 26.6.2\n",
+		enum dcp_firmware_version version;
+
+		if (ret >= 0 && compat_ret >= 0) {
+			version = dcp_t6041_firmware_version(fw_str, compat_str);
+			if (version == DCP_FIRMWARE_V_27_0 &&
+			    !dcp_v27_method_table_supported(dev, compat_str))
+				return DCP_FIRMWARE_UNKNOWN;
+			if (version != DCP_FIRMWARE_UNKNOWN)
+				return version;
+		}
+		dev_err(dev, "T6041 display not started: unsupported DCP firmware %s (compat %s)\n",
 			ret >= 0 ? fw_str : "missing",
 			compat_ret >= 0 ? compat_str : "missing");
 		return DCP_FIRMWARE_UNKNOWN;
@@ -5812,16 +5842,18 @@ static int dcp_comp_bind_pipe(struct device *dev, struct device *main, void *dat
 		panel_np = of_get_compatible_child(dev->of_node, "apple,panel");
 
 	if (panel_np) {
-		if (dcp->fw_compat == DCP_FIRMWARE_V_26_6_DESKTOP) {
+		if (dcp->fw_compat == DCP_FIRMWARE_V_26_6_DESKTOP ||
+		    (dcp->fw_compat == DCP_FIRMWARE_V_27_0 &&
+		     of_device_is_compatible(dcp->dev->of_node, "apple,t6041-dcp"))) {
 			/*
-			 * Desktop 26.x swaps carry nits, and the panel node
-			 * describes the panel whether or not the boot loader
-			 * enabled it.  Without apple,max-brightness take the
-			 * J616s panel's user-accessible SDR maximum.
+			 * The T6041 panel node has no apple,max-brightness in
+			 * either firmware lineage. Use its user-accessible SDR
+			 * maximum; firmware 27 takes the peak and EDR headroom
+			 * from ADT below.
 			 */
 			if (of_property_read_u32(panel_np, "apple,max-brightness",
 						 &dcp->brightness.maximum))
-				dcp->brightness.maximum = DCP_DESKTOP_MAX_NITS;
+				dcp->brightness.maximum = DCP_T6041_MAX_NITS;
 		} else if (of_device_is_available(panel_np)) {
 			ret = of_property_read_u32(panel_np, "apple,max-brightness",
 						   &dcp->brightness.maximum);
@@ -5831,7 +5863,7 @@ static int dcp_comp_bind_pipe(struct device *dev, struct device *main, void *dat
 
 		dcp_panel_read_dimensions(dcp, panel_np);
 		of_node_put(panel_np);
-		/* Read target metadata for H17P and desktop firmware alike. */
+		/* Read target metadata for firmware 27 and desktop firmware alike. */
 		dcp_panel_read_adt(dcp);
 		dcp->fixed_connector_type = DRM_MODE_CONNECTOR_eDP;
 		dcp->connector_type = DRM_MODE_CONNECTOR_eDP;
@@ -6401,7 +6433,7 @@ static int dcp_platform_probe_pipe(struct platform_device *pdev)
 	fw_compat = dcp_check_firmware_version(dev);
 	if (fw_compat == DCP_FIRMWARE_UNKNOWN)
 		return -ENODEV;
-	if (fw_compat == DCP_FIRMWARE_V_26_6_DESKTOP) {
+	if (of_device_is_compatible(dev->of_node, "apple,t6041-dcp")) {
 		ret = dcp_validate_t6041_dt(dev);
 		if (ret)
 			return ret;
@@ -6500,6 +6532,11 @@ static int dcp_platform_probe_pipe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 	dcp->hw = *(struct apple_dcp_hw_data *)of_device_get_match_data(dev);
+	/* T6041 firmware 27 is the inherited live-session path, like T6050. */
+	if (fw_compat == DCP_FIRMWARE_V_27_0 &&
+	    (of_device_is_compatible(dev->of_node, "apple,t6041-dcp") ||
+	     of_device_is_compatible(dev->of_node, "apple,t6041-dcpext")))
+		dcp->hw.adopt_live_session = true;
 	/*
 	 * T8142 on firmware 27 runs as the T6050's firmware-27 instance, with
 	 * the default method profile: with H17G every swap fails with status 4.
@@ -8877,7 +8914,7 @@ static const struct apple_dcp_hw_data apple_dcp_hw_t8132_dcpext = {
 };
 #endif
 
-/* T6041 (M4 Pro/Max), desktop 26.6 firmware */
+/* T6041 (M4 Pro/Max), selected at probe between desktop 26.x and firmware 27. */
 static const struct apple_dcp_hw_data apple_dcp_hw_t6041 = {
 	.num_dptx_ports = 2,
 };

drivers/gpu/drm/apple/dcp.h

@@ -90,6 +90,8 @@ bool dcp_fw_compat_is_14_7(struct platform_device *pdev);
 bool dcp_fw_compat_is_desktop(struct platform_device *pdev);
 bool dcp_fw_compat_panel_edr(struct platform_device *pdev);
 unsigned int dcp_gamma_lut_size(struct platform_device *pdev);
+enum dcp_firmware_version dcp_t6041_firmware_version(const char *firmware,
+						      const char *compat);
 /* T6041 external display processors may join the DRM device. */
 bool dcp_t6041_ext_enabled(void);
 void dcp_backlight_takeover_registered(struct platform_device *pdev);

drivers/gpu/drm/apple/iomfb_v27.c

@@ -119,9 +119,9 @@ static const struct dcp_method_entry dcp_methods_27_0[dcpep_num_methods] = {
  * A400/A401, so IOMobileFramebufferAP moved up by 50 (start_signal A451,
  * get_color_remap_mode A477), and set_create_DFB and vi_set_temperature_hint
  * up by one. The UPPipe A0xx and A1xx IDs are unchanged. The firmware rejects
- * an unknown tag with a panic ("link_rpc_lookup callback not found"), so
- * dfb_ready_query, whose 27.2 tag has not been seen in a call, has no entry
- * here and is not sent to this build (boot_5()).
+ * an unknown tag with a panic ("link_rpc_lookup callback not found").
+ * dfb_ready_query is A385, one above its 27.0 ID: the 27.3 trace sends it
+ * there, and the J813's DCP answers it at A385 on 27.2.
  */
 static const struct dcp_method_entry dcp_methods_27_2[dcpep_num_methods] = {
 	IOMFB_METHOD("A000", dcpep_late_init_signal),
@@ -147,6 +147,7 @@ static const struct dcp_method_entry dcp_methods_27_2[dcpep_num_methods] = {
 	IOMFB_METHOD("A104", dcpep_set_dfb_dimensions),
 	IOMFB_METHOD("A105", dcpep_commit_dfb_info),
 	IOMFB_METHOD("A035", dcpep_dfb_query),
+	IOMFB_METHOD("A385", dcpep_dfb_ready_query),
 	IOMFB_METHOD("A353", dcpep_pipe_query_353),
 	IOMFB_METHOD("A352", dcpep_pipe_set_352),
 	IOMFB_METHOD("A465", dcpep_pipe_cfg_415),
@@ -601,6 +602,12 @@ static const iomfb_cb_handler cb_handlers[IOMFB_MAX_CB] = {
 	[587] = trampoline_nop,
 	[588] = trampoline_nop,
 	[589] = trampoline_swap_info_h17p,
+	/*
+	 * 27.2 sends this 20-byte notification with no reply after swaps (the
+	 * macOS handler next to swap_info is the buffer-release notification);
+	 * nothing here consumes it.
+	 */
+	[590] = trampoline_nop,
 
 	[592] = trampoline_nop,
 	[594] = trampoline_swap_complete,
@@ -687,6 +694,7 @@ static const struct {
 	[587] = { 0x0, 0x0 },
 	[588] = { 0x18, 0x0 },
 	[589] = { 0xe4, 0xe0 },
+	[590] = { 0x14, 0x0 },
 	[592] = { 0x0, 0x0 },
 	[594] = { 0x730, 0x0 },
 	[596] = { 0x14, 0x0 },

drivers/gpu/drm/apple/iomfb_v27_test.c

@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0-only OR MIT
+/* Copyright 2026 Aurora Silicon */
+
+#include <kunit/test.h>
+#include <linux/module.h>
+
+#include "dcp.h"
+#include "iomfb.h"
+#include "iomfb_v27.h"
+
+static void v27_method_table_test(struct kunit *test)
+{
+	const struct dcp_method_entry *methods;
+	unsigned int missing;
+
+	methods = iomfb_v27_methods("27.2.0");
+	KUNIT_ASSERT_NOT_NULL(test, methods);
+	KUNIT_EXPECT_MEMEQ(test, methods[dcpep_dfb_ready_query].tag, "A385", 4);
+	KUNIT_EXPECT_PTR_EQ(test, iomfb_v27_missing_method(methods, &missing), NULL);
+	KUNIT_EXPECT_EQ(test, missing, 0U);
+	KUNIT_EXPECT_PTR_EQ(test, iomfb_v27_methods("27.1.0"), NULL);
+}
+
+static void v27_d590_callback_test(struct kunit *test)
+{
+	KUNIT_EXPECT_TRUE(test, iomfb_v27_callback_size_valid(590, 20, 0));
+	KUNIT_EXPECT_FALSE(test, iomfb_v27_callback_size_valid(590, 19, 0));
+}
+
+static void t6041_firmware_admission_test(struct kunit *test)
+{
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("26.5.2", "26.5.2"),
+			DCP_FIRMWARE_V_26_6_DESKTOP);
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("26.6.2", "26.6.2"),
+			DCP_FIRMWARE_V_26_6_DESKTOP);
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("27.2.0", "27.2.0"),
+			DCP_FIRMWARE_V_27_0);
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("27.2.1", "27.2.0"),
+			DCP_FIRMWARE_V_27_0);
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("26.6.2", "27.2.0"),
+			DCP_FIRMWARE_V_27_0);
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("27.0.0", "27.0.0"),
+			DCP_FIRMWARE_UNKNOWN);
+	KUNIT_EXPECT_EQ(test,
+			dcp_t6041_firmware_version("26.6.2", "26.5.2"),
+			DCP_FIRMWARE_UNKNOWN);
+}
+
+static struct kunit_case v27_cases[] = {
+	KUNIT_CASE(v27_method_table_test),
+	KUNIT_CASE(v27_d590_callback_test),
+	KUNIT_CASE(t6041_firmware_admission_test),
+	{}
+};
+
+static struct kunit_suite v27_suite = {
+	.name = "apple-dcp-v27",
+	.test_cases = v27_cases,
+};
+
+kunit_test_suite(v27_suite);
+
+MODULE_LICENSE("Dual MIT/GPL");

drivers/soc/apple/Kconfig

@@ -355,7 +355,8 @@ config APPLE_DISPLAY_GATE
 
 	  On T6041 (M4 Pro) device trees it enables the internal display nodes
 	  only when the boot loader has handed the running display coprocessor
-	  over (apple,t6041-handoff, 26.6.2 display firmware), and powers up
+	  over (apple,t6041-handoff, qualified 26.6.2 or 27.2 display firmware),
+	  and powers up
 	  the J616s external display chain (HDMI, Type-C DisplayPort) once the
 	  boot loader has given the external display processors their
 	  firmware memory. Without these, or with nomodeset, it does nothing.

drivers/soc/apple/display-gate-test.c

@@ -1014,8 +1014,22 @@ static void __init gate_t6041_staged_steps(struct kunit *test)
 				    "step %u", i);
 }
 
+static void __init gate_t6041_firmware_compat_test(struct kunit *test)
+{
+	const u32 desktop[] = { 26, 6, 2 };
+	const u32 v27[] = { 27, 2, 0 };
+	const u32 old[] = { 26, 5, 2 };
+	const u32 unknown[] = { 27, 3, 0 };
+
+	KUNIT_EXPECT_TRUE(test, gate_t6041_firmware_compat(desktop));
+	KUNIT_EXPECT_TRUE(test, gate_t6041_firmware_compat(v27));
+	KUNIT_EXPECT_FALSE(test, gate_t6041_firmware_compat(old));
+	KUNIT_EXPECT_FALSE(test, gate_t6041_firmware_compat(unknown));
+}
+
 static struct kunit_case gate_t6041_cases[] __refdata = {
 	KUNIT_CASE(gate_t6041_staged_steps),
+	KUNIT_CASE(gate_t6041_firmware_compat_test),
 	{}
 };
 

drivers/soc/apple/display-gate.c

@@ -2092,10 +2092,10 @@ static void __init gate_run(void)
 /*
  * T6041 internal display. The handoff describes the DCP that iBoot left
  * running: the DCP, the display subsystem and the DCP's piodma child carry
- * the marker, the DCP names the 26.6.2 firmware the desktop IOMFB instance is
- * written for, and the DCP, display and piodma streams sit on the expected
- * DARTs. The display nodes are enabled only when all of that checks out and
- * the DCP is running.
+ * the marker, the DCP names a qualified 26.6.2 or 27.2 firmware interface,
+ * and the DCP, display and piodma streams sit on the expected DARTs. The
+ * display nodes are enabled only when all of that checks out and the DCP is
+ * running.
  */
 #define T6041_DCP_SID		23
 #define T6041_DISP_SID		0
@@ -2115,6 +2115,12 @@ static const int t6041_enable[] __initconst = { T6041_DCP_DART, T6041_DISP_DART,
 /* Applied, it stays: the live tree refers to it. */
 static struct of_changeset t6041_gate;
 
+static bool __init gate_t6041_firmware_compat(const u32 version[3])
+{
+	return (version[0] == 26 && version[1] == 6 && version[2] == 2) ||
+	       (version[0] == 27 && version[1] == 2 && version[2] == 0);
+}
+
 static void __init gate_t6041_internal(void)
 {
 	struct device_node *nodes[T6041_NR_NODES] = {};
@@ -2139,10 +2145,10 @@ static void __init gate_t6041_internal(void)
 	    !gate_marked(nodes[T6041_PIODMA]))
 		goto out;
 
-	/* The desktop IOMFB instance is written for the 26.6.2 firmware only. */
+	/* Admit the transition desktop ABI and the firmware-27 ABI. */
 	if (of_property_count_u32_elems(nodes[T6041_DCP], "apple,firmware-compat") != 3 ||
 	    of_property_read_u32_array(nodes[T6041_DCP], "apple,firmware-compat", version, 3) ||
-	    version[0] != 26 || version[1] != 6 || version[2] != 2)
+	    !gate_t6041_firmware_compat(version))
 		goto out;
 
 	nodes[T6041_DCP_DART] = gate_target(nodes[T6041_DCP], "iommus", "#iommu-cells",