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Sat, 14 Nov 2026 08:09:22 -0800 (PST) Received: from at-Standard-PC-Q35-ICH9-2009 ([106.202.127.108]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-37956bb0919sm17567582eec.29.2026.11.14.08.09.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Nov 2026 08:09:21 -0800 (PST) From: Atharva Tiwari To: Cc: Andre Eikmeyer , Sebastian Zygadlo , Yossef Osman , Atharva Tiwari , Bjorn Helgaas , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org (maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)), "H. Peter Anvin" , Alex Deucher , =?UTF-8?q?Christian=20K=C3=B6nig?= , David Airlie , Simona Vetter , Harry Wentland , Leo Li , Rodrigo Siqueira , Kenneth Feng , Hans de Goede , =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= , linux-pci@vger.kernel.org (open list:PCI SUBSYSTEM), linux-kernel@vger.kernel.org (open list:X86 ARCHITECTURE (32-BIT AND 64-BIT)), amd-gfx@lists.freedesktop.org (open list:RADEON and AMDGPU DRM DRIVERS), dri-devel@lists.freedesktop.org (open list:DRM DRIVERS), platform-driver-x86@vger.kernel.org (open list:X86 PLATFORM DRIVERS) Subject: [PATCH v2 05/12] platform/apple-gmux: Write switch state to EFI on MMIO devices Date: Sat, 14 Nov 2026 11:06:29 -0500 Message-ID: <20261114160731.3756-6-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261114160731.3756-1-atharvatiwarilinuxdev@gmail.com> References: <20261114160731.3756-1-atharvatiwarilinuxdev@gmail.com> X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Andre Eikmeyer On T2 devices (MMIO), the T2 coprocessor reads gpu-active efi variable, and macOS seems to write it, so to properly communciate to the T2 coprocessor, we write gpu-active. Tested-by: Sebastian Zygadlo Tested-by: Yossef Osman Co-developed: Atharva Tiwari Signed-off-by: Atharva Tiwari Signed-off-by: Andre Eikmeyer --- drivers/platform/x86/Kconfig | 1 + drivers/platform/x86/apple-gmux.c | 40 +++++++++++++++++++++++++++++++ 2 files changed, 41 insertions(+) diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig index c37e76066..01895d511 100644 --- a/drivers/platform/x86/Kconfig +++ b/drivers/platform/x86/Kconfig @@ -217,6 +217,7 @@ config APPLE_GMUX depends on ACPI && PCI depends on PNP depends on BACKLIGHT_CLASS_DEVICE + depends on EFI help This driver provides support for the gmux device found on many Apple laptops, which controls the display mux for the hybrid diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 37ba20779..c4a953b5b 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -26,6 +26,7 @@ #include #include #include +#include #include #include @@ -489,6 +490,32 @@ static void gmux_write_switch_state(struct apple_gmux_data *gmux_data) gmux_write8(gmux_data, GMUX_PORT_SWITCH_EXTERNAL, 3); } +#define APPLE_GPU_VARS_GUID EFI_GUID(0xfa4ce28d, 0xb62f, 0x4c99, \ + 0x9c, 0xc3, 0x68, 0x15, 0x68, 0x6e, 0x30, 0xf9) + +static efi_char16_t gmux_gpu_active_name[] = L"gpu-active"; + +static void gmux_write_switch_state_efi(struct apple_gmux_data *gmux_data) +{ + efi_guid_t guid = APPLE_GPU_VARS_GUID; + u32 active = gmux_data->switch_state_display == VGA_SWITCHEROO_IGD; + efi_status_t status; + + if (!efivar_is_available() || + !efi_rt_services_supported(EFI_RT_SUPPORTED_SET_VARIABLE)) + return; + + status = efivar_set_variable(gmux_gpu_active_name, &guid, + EFI_VARIABLE_NON_VOLATILE | + EFI_VARIABLE_BOOTSERVICE_ACCESS | + EFI_VARIABLE_RUNTIME_ACCESS, + sizeof(active), &active); + if (status != EFI_SUCCESS) + pr_warn("writing gpu-active failed: 0x%lx\n", status); + else + pr_debug("gpu-active: %u\n", active); +} + static int gmux_switchto(enum vga_switcheroo_client_id id) { apple_gmux_data->switch_state_ddc = id; @@ -497,6 +524,8 @@ static int gmux_switchto(enum vga_switcheroo_client_id id) apple_gmux_data->switch_state_external = id; gmux_write_switch_state(apple_gmux_data); + if (apple_gmux_data->type == APPLE_GMUX_TYPE_MMIO) + gmux_write_switch_state_efi(apple_gmux_data); return 0; } @@ -1240,6 +1269,15 @@ static void gmux_remove(struct pnp_dev *pnp) kfree(gmux_data); } +static void gmux_shutdown(struct pnp_dev *pnp) +{ + struct apple_gmux_data *gmux_data = pnp_get_drvdata(pnp); + + gmux_write_switch_state_efi(gmux_data); + + gmux_remove(pnp); +} + static const struct pnp_device_id gmux_device_ids[] = { { .id = GMUX_ACPI_HID }, { } @@ -1254,6 +1292,7 @@ static struct pnp_driver gmux_pnp_driver = { .name = "apple-gmux", .probe = gmux_probe, .remove = gmux_remove, + .shutdown = gmux_shutdown, .id_table = gmux_device_ids, .driver = { .pm = &gmux_dev_pm_ops, @@ -1265,3 +1304,4 @@ MODULE_AUTHOR("Seth Forshee "); MODULE_DESCRIPTION("Apple Gmux Driver"); MODULE_LICENSE("GPL"); MODULE_DEVICE_TABLE(pnp, gmux_device_ids); +MODULE_IMPORT_NS("EFIVAR"); -- 2.55.0