From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=74.125.82.49 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794672354; b=S7PUoL59fA50RCZwDQpBGeM0tEiezy8PupUysB+0GiMHNdSIsS2nNfvzfI4euYprhuZo N5ETZGpNxmlWIKE+cZrQLXIqKc7ADs8Pl4oKUWSK28V+6uuE4iXmwM6wRvT2QjZNtlAsB sJNTbPUwagowKGI4k5vjH98uxaFfremX8nMBXrT82Sk7rqRzbkasrlKy4kzdzcTcZhEe5 GZ5pOs0wz697JeV+5F717GW62e1DbsuIdamhbVfJqyfYqd7V1VOvR5AKmztDSERri1jbl JRNe14YVdDghEB7F9aUET+ZBNrM2txlA0q7sR9Kb0k5hn0267JLRmWj9Id+rCVF9c1g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794672354; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-ID:X-Mailer:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding; bh=rwXxXGuI8odA6JxbQFYflPGUh67I5rWeLK+lGKx8MRg=; b=zJ2DK1LX7VrL4Jyoyn9x3p7wfLU9uf4LVEL3IFYuWrtUg9rJFnCJCg79gXQIm6w8e4Lp NAksFWEodkE0Zaw6nM8aYKeczNnpMXT3ylc4bgPdQtUQFlZtrp+DQu4U/fIe9ZBumwX2G +l9Qfrb9nmUrwEVocWn7ryzsS4kqnjFY36eGMHxSUF60/IVE8yABmw3lV8rpnCRDctWXr wrZ7/yyYVyaOVkpwbuy7vFMccQHUPjiTU1rfWDB8tiE4CzzD2lQLQO8EKuS7bH/hJRshe aMnSTDpBGzTqzZGersTdMMnZ5YopYGO22Ss63mrJ4a46T/JfjD7a+ThzdGvFMkn0InA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=ylt25xxI; arc=none smtp.remote-ip=74.125.82.49 Received: from mail-dl1-f49.google.com (mail-dl1-f49.google.com [74.125.82.49]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9388E606A329 for ; Sat, 14 Nov 2026 16:05:54 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9388E606A329 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=ylt25xxI Received: by mail-dl1-f49.google.com with SMTP id a92af1059eb24-1a3c08d6928so2740340c88.0 for ; Sat, 14 Nov 2026 08:05:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1794672354; x=1795277154; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=rwXxXGuI8odA6JxbQFYflPGUh67I5rWeLK+lGKx8MRg=; b=ylt25xxIBag8hj1X6iBLXaTpMY5Pb0x9gWZ9v811l2u2hHhfwwFVcmDKQXepxHIRwX c7PyaEK9KIy3GU77RlSxBsezWsRbkN21rabe7XYhjAETrN7wW9KP4nWH3/TPVufNzUfd 35t1OD8UXG5J15P4SqlR6T6XOvhd49FQe0PRVY8EzlvKtUTbN9WIJRn8mrvRjBHRmrBZ GCP3W2aJfwPBRm8m1Tfd6LSkSbx/N6DqActZwrJccRYgaVjo0GKTAdjnQyZoFucqoIdr /G/Pb8WOS+3R2GE8c/PCNJn2mJt6Q9B5bAp718IUyI1kGJ5L8LCuBrkT1di1k/pcvR+i Bniw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794672354; x=1795277154; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=rwXxXGuI8odA6JxbQFYflPGUh67I5rWeLK+lGKx8MRg=; b=StNv08gksksj22stWQL6pNiL9qIQ6GGe/i13y5eJvjHdvSloowY/o7Fwav0wtcuGsC Ziw0fDI6a3NZwZpqBzAHhEPw+/a/L1o6zN/q+zbACWRqUrj2F9pab0h1AO/Hab60uwKi Hrly6Fj8dCP2BFmdRQBZRZ6ioN1jL52HgJJVLkceDKUZ54mXVcUIoGCGKlizAJ6MXs/u fF1hn329SIT5tkvXIWif1sjHCLRex6lwJDSgbQx6QIeSG7EdJRaYCHtHd4ntQxpop4bG 1dMplCnjZOfxihE5K5XTLW1DCO8S9Y8EN83m0ppX4xE5MrC/yor5B3baAAaHrQLMiuqR MMlw== X-Forwarded-Encrypted: i=1; AL+hErEqfJkeGS7reI9i4JRKAPFfHPhz9wrWOZIk6nR9zFJ3svZbwOwxIGQp0Bb6ri5DBWsKBY4gZwrqgik=@vger.kernel.org X-Gm-Message-State: APuU4Z8iqH8OmPKI+dnpRKneJ/UqMxS1SbNZz3JXYuKQBQxgX1E2crUP eonvKjv1eDvggYhzL0fgr4SLGOm7kYKivqiNKxzqnBKuEXvQk5lElqM= X-Gm-Gg: AYBFou11KfGVe+eYfo+9pLx7P7jA6zUcpcwU5yYqXHWbtu4CxZQEuHToP2DqeF6vLsi PPSe6xp5U5cGrPTahk8/osit3/F0BKllQqyQKKkjBRMcgQBicI7IpDf14Tf/iLB3llvZNFroMe4 Z12b4whemNOpDPGytPCaBHDMM8b7dGm8LAduREi7phSWy+FHKAbcHZrBCQP1pc8gJ9TA4Ri2Gh5 FZX9NuzCyrCZhrR91p2hwF3A9IUgqcEE+I4pPH+nR/wC6wRnCVuEYkABqsQ6N0NLngD6h+hNogi qTXmOYzEq35bRWfw2WRqNJEJ1XyZK32M+IYZO2C+8MG8cacQYNaQio4d9vyEba0jhhMiwpWAdGj 9uogh+V3/+kcrRqvvu56XcDrp5lltqZjKV+C744cexREMn3aXFS0B1DUaj/xZ3RiD61q6BL5sUo XUTXz5S/N0ffqjewoc2jz2vqvHAh7lPycDCaguoUxml1/CQZkeG2ZQ862989X9m8vntyAsxvztA IPg1pXp5EeOOfGa7ibapxHQdoi+6SYxROWNEhk9NOZRb71nxHHHzYeJRBbvjRxBpkrKGE8nA4Rx vLmgUNpiMnRJ9RtQb+W/Q6KoqrRP4IAf9bajY8t92E2yY5Aa3X95+hvTTc+QVEqLEg== X-Received: by 2002:a05:7023:d0a:b0:1a4:fac9:aeee with SMTP id a92af1059eb24-1b50302aba6mr5983738c88.4.1794672353408; Sat, 14 Nov 2026 08:05:53 -0800 (PST) Received: from at-Standard-PC-Q35-ICH9-2009 ([106.202.114.179]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-1b505b5bf76sm13378548c88.10.2026.11.14.08.05.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Nov 2026 08:05:53 -0800 (PST) From: Atharva Tiwari To: Cc: Atharva Tiwari , Sebastian Zygadlo , Yossef Osman , Andre Eikmeyer , 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 01/12] platform/apple-gmux: Fix power for MMIO systems Date: Sat, 14 Nov 2026 11:03:48 -0500 Message-ID: <20261114160457.3034-2-atharvatiwarilinuxdev@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20261114160457.3034-1-atharvatiwarilinuxdev@gmail.com> References: <20261114160457.3034-1-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 Currently The dGPU on MMIO Systems, dies when we write the gmux values to turn off the gpu. On MMIO macs Using only gmux dosent work, instead we have to use PWRD method + GMUX, which turns off the entire bridge, and completely messes the pci config, so we can't use pci to traverse through it. we save the entire bridge using ACPI addresses then we run PWRD(1) to turn off the bridge, then we write gmux states, and resume we do the vice versa, but here we dont need to retrain the link and write the MMIO variable. Tested-by: Sebastian Zygadlo Tested-by: Yossef Osman Co-developed-by: Andre Eikmeyer Signed-off-by: Andre Eikmeyer Signed-off-by: Atharva Tiwari --- drivers/platform/x86/apple-gmux.c | 159 ++++++++++++++++++++++++++++-- 1 file changed, 152 insertions(+), 7 deletions(-) diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c index 9c728ac4e..34e94f2b2 100644 --- a/drivers/platform/x86/apple-gmux.c +++ b/drivers/platform/x86/apple-gmux.c @@ -65,6 +65,10 @@ struct apple_gmux_data { struct backlight_device *bdev; + /* power handling data */ + struct pci_dev *discrete_pdev; + enum apple_gmux_type type; + /* switcheroo data */ acpi_handle dhandle; int gpe; @@ -502,23 +506,158 @@ static int gmux_switch_ddc(enum vga_switcheroo_client_id id) /** * DOC: Power control * - * gmux is able to cut power to the discrete GPU. It automatically takes care + * gmux is able to cut power to the discrete GPU. On most + * Systems the gmux automatically takes care * of the correct sequence to tear down and bring up the power rails for * core voltage, VRAM and PCIe. + * + * But on MMIO systems, the standard gmux writes does not work instead we + * have to use a combination of ACPI and GMUX, + * and Using PWRD (the method that used in macOS to turn on/off the dGPU and its bridges), + * which turns off the entire bridge and messes up the PCI config, + * so we can't use pci_upstream_bridge to traverse + * through the bridge, so we use ACPI addresses to save/restore bridges. + * + * NOTE: Communication to these bridges (not the dGPU/HDA) in any form + * when the bridge is off, will result in CPU CATERR. */ +static int gmux_save_restore_pci(acpi_handle parent_handle, const char *name, + bool save, acpi_handle *out_handle) +{ + acpi_status status; + acpi_handle handle; + struct acpi_device *adev; + struct device *dev; + struct pci_dev *pdev; + + if (name) { + status = acpi_get_handle(parent_handle, name, &handle); + if (ACPI_FAILURE(status)) + return -EIO; + + if (out_handle) + *out_handle = handle; + } else + handle = parent_handle; + + adev = acpi_fetch_acpi_dev(handle); + if (!adev) + return -EIO; + + dev = acpi_get_first_physical_node(adev); + if (!dev || !dev_is_pci(dev)) + return -EIO; + + pdev = to_pci_dev(dev); + + if (save) { + pci_save_state(pdev); + pdev->current_state = PCI_D3cold; + } else { + pdev->current_state = PCI_D0; + pci_restore_state(pdev); + } + return 0; +} + static int gmux_set_discrete_state(struct apple_gmux_data *gmux_data, enum vga_switcheroo_state state) { reinit_completion(&gmux_data->powerchange_done); + acpi_handle discrete_handle; + acpi_status status; + unsigned long long result; + + if (!gmux_data->discrete_pdev) + return -ENODEV; + + discrete_handle = ACPI_HANDLE(&gmux_data->discrete_pdev->dev); + if (!discrete_handle) + return -ENODEV; if (state == VGA_SWITCHEROO_ON) { - gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); - gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3); + if (gmux_data->type == APPLE_GMUX_TYPE_MMIO) { + acpi_handle handle; + u16 vendor; + int i; + + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 2); + msleep(100); + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3); + + status = acpi_execute_simple_method(discrete_handle, "PWRD", 0); + if (ACPI_FAILURE(status)) + return -EIO; + msleep(20); + + if (gmux_save_restore_pci(NULL, "\\_SB_.PCI0.PEG0", 0, &handle)) + return -EIO; + + if (gmux_save_restore_pci(handle, "EGP0", 0, &handle)) + return -EIO; + + if (gmux_save_restore_pci(handle, "EGP1", 0, &handle)) + return -EIO; + + for (i = 0; i < 1000; i++) { + pci_read_config_word(gmux_data->discrete_pdev, + PCI_VENDOR_ID, &vendor); + if (vendor != 0xffff) + break; + msleep(1); + } + if (vendor == 0xffff) + return -ETIMEDOUT; + + if (gmux_save_restore_pci(handle, "GFX0", 0, NULL)) + return -EIO; + + if (gmux_save_restore_pci(handle, "HDAU", 0, NULL)) + return -EIO; + } else { + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 3); + } pr_debug("Discrete card powered up\n"); } else { - gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); - gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 0); + if (gmux_data->type == APPLE_GMUX_TYPE_MMIO) { + acpi_handle parent_handle = discrete_handle; + bool saved_hda = false; + + /* If the power state was OFF, then we only do + * PWRD and we do not save registers, as the + * registers are already saved + */ + if (gmux_data->power_state == VGA_SWITCHEROO_OFF) + goto do_pwrd; + + while (ACPI_SUCCESS(acpi_get_parent(parent_handle, + &parent_handle))) { + if (!saved_hda) { + if (!gmux_save_restore_pci(parent_handle, + "HDAU", true, NULL)) { + saved_hda = true; + pci_save_state(gmux_data->discrete_pdev); + gmux_data->discrete_pdev->current_state = + PCI_D3cold; + } + } + if (gmux_save_restore_pci(parent_handle, NULL, true, NULL)) + break; + } +do_pwrd: + status = acpi_execute_simple_method(discrete_handle, "PWRD", 1); + if (ACPI_FAILURE(status)) + return -EIO; + msleep(20); + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); + mdelay(10); + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 0); + } else { + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 1); + gmux_write8(gmux_data, GMUX_PORT_DISCRETE_POWER, 0); + } pr_debug("Discrete card powered down\n"); } @@ -552,10 +691,14 @@ static enum vga_switcheroo_client_id gmux_get_client_id(struct pci_dev *pdev) else if (pdev->vendor == PCI_VENDOR_ID_NVIDIA && pdev->device == 0x0863) return VGA_SWITCHEROO_IGD; - else + else { + if (!apple_gmux_data->discrete_pdev) + apple_gmux_data->discrete_pdev = pci_dev_get(pdev); + return VGA_SWITCHEROO_DIS; -} + } +} static const struct vga_switcheroo_handler gmux_handler_no_ddc = { .switchto = gmux_switchto, .power_state = gmux_set_power_state, @@ -803,6 +946,7 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) if (!gmux_data) return -ENOMEM; pnp_set_drvdata(pnp, gmux_data); + gmux_data->type = type; switch (type) { case APPLE_GMUX_TYPE_MMIO: @@ -993,6 +1137,7 @@ static void gmux_remove(struct pnp_dev *pnp) gmux_fini_debugfs(gmux_data); vga_switcheroo_unregister_handler(); + pci_dev_put(gmux_data->discrete_pdev); gmux_disable_interrupts(gmux_data); if (gmux_data->gpe >= 0) { acpi_disable_gpe(NULL, gmux_data->gpe); -- 2.55.0