From patchwork Thu Jan 6 00:06:53 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bjorn Helgaas X-Patchwork-Id: 12704901 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D2B22C433F5 for ; Thu, 6 Jan 2022 00:07:36 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6269C10E534; Thu, 6 Jan 2022 00:07:25 +0000 (UTC) Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7663110E53A for ; Thu, 6 Jan 2022 00:07:23 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id ECDD5619C2; Thu, 6 Jan 2022 00:07:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E9B32C36AED; Thu, 6 Jan 2022 00:07:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1641427641; bh=FzOZFXfRW7iKLHtKUv+FE2m7xC0KfPGeO0MaK0M98W4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o0qhmJ3j/G2mtIHKxxqDDBK1w8cAKjIiIDTOyQxWV9nWlovR9m7yu+gurMc+WaHLx Gr00tvZAi7o51MYsw0ADN20Em4bZxOutyOV0QG+B+mKt3DLmn1yAnTQpD8DF0NChbU KGY+fDB8UbgkxgAasbJj05PMqIDilNVE29GmnyRz1AlXgI6YxbcYifjba7dimxKo8j IpuEM2z4nEHSQvFts9jJt0jpbPPZyFsFejCnCoYXG8BTm/nZtoo7jnTgM4GB4/HvDf HODbQ8iOYMBq8St2dhxt/PR8TSLdP5TSFyozomgJrQ22prL7gFYb71IAHmqnX/JTmS e1WFrCEPqvLOQ== From: Bjorn Helgaas To: David Airlie , Daniel Vetter Subject: [PATCH v8 05/10] vgaarb: Move non-legacy VGA detection to ADD_DEVICE path Date: Wed, 5 Jan 2022 18:06:53 -0600 Message-Id: <20220106000658.243509-6-helgaas@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220106000658.243509-1-helgaas@kernel.org> References: <20220106000658.243509-1-helgaas@kernel.org> MIME-Version: 1.0 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-pci@vger.kernel.org, Huacai Chen , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Zhou Wang , Bjorn Helgaas , Daniel Axtens , Xuefeng Li , Huacai Chen Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Bjorn Helgaas a37c0f48950b ("vgaarb: Select a default VGA device even if there's no legacy VGA") extended the vga_arb_device_init() subsys_initcall so it could select a non-legacy VGA device as the default. That failed to consider that PCI devices may be enumerated after vga_arb_device_init(), e.g., hot-added devices or non-ACPI systems that do PCI enumeration in pcibios_init(). Devices found then could never be selected as the default. One system where this is a problem is the MIPS-based Loongson where an ASpeed AST2500 VGA device is behind a bridge that doesn't implement the VGA Enable bit, so legacy resources are not routed to the VGA device. [1] Fix this by moving the non-legacy VGA device selection from vga_arb_select_default_device() to vga_arbiter_add_pci_device(), which is called after every PCI device is enumerated, either by the vga_arb_device_init() subsys_initcall or as an ADD_DEVICE notifier. [1] https://lore.kernel.org/r/20210514080025.1828197-6-chenhuacai@loongson.cn Link: https://lore.kernel.org/r/20211015061512.2941859-5-chenhuacai@loongson.cn Link: https://lore.kernel.org/r/20211015061512.2941859-7-chenhuacai@loongson.cn Based-on-patch-by: Huacai Chen Signed-off-by: Bjorn Helgaas Cc: Daniel Axtens Cc: Zhou Wang --- drivers/gpu/vga/vgaarb.c | 54 ++++++++++++++++++++++++---------------- 1 file changed, 32 insertions(+), 22 deletions(-) diff --git a/drivers/gpu/vga/vgaarb.c b/drivers/gpu/vga/vgaarb.c index aefa4f406f7d..123b81628061 100644 --- a/drivers/gpu/vga/vgaarb.c +++ b/drivers/gpu/vga/vgaarb.c @@ -624,6 +624,7 @@ static bool vga_is_boot_device(struct vga_device *vgadev) { struct vga_device *boot_vga = vgadev_find(vga_default_device()); struct pci_dev *pdev = vgadev->pdev; + u16 cmd, boot_cmd; /* * We select the default VGA device in this order: @@ -661,6 +662,37 @@ static bool vga_is_boot_device(struct vga_device *vgadev) if ((vgadev->owns & VGA_RSRC_LEGACY_MASK) == VGA_RSRC_LEGACY_MASK) return true; + /* + * If we haven't found a legacy VGA device, accept a non-legacy + * device. It may have either IO or MEM enabled, and bridges may + * not have PCI_BRIDGE_CTL_VGA enabled, so it may not be able to + * use legacy VGA resources. Prefer an integrated GPU over others. + */ + pci_read_config_word(pdev, PCI_COMMAND, &cmd); + if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) { + + /* + * An integrated GPU overrides a previous non-legacy + * device. We expect only a single integrated GPU, but if + * there are more, we use the *last* because that was the + * previous behavior. + */ + if (vga_arb_integrated_gpu(&pdev->dev)) + return true; + + /* + * We prefer the first non-legacy discrete device we find. + * If we already found one, vgadev is no better. + */ + if (boot_vga) { + pci_read_config_word(boot_vga->pdev, PCI_COMMAND, + &boot_cmd); + if (boot_cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) + return false; + } + return true; + } + return false; } @@ -1529,30 +1561,8 @@ static struct miscdevice vga_arb_device = { static void __init vga_arb_select_default_device(void) { - struct pci_dev *pdev, *found = NULL; struct vga_device *vgadev; - if (!vga_default_device()) { - list_for_each_entry_reverse(vgadev, &vga_list, list) { - struct device *dev = &vgadev->pdev->dev; - u16 cmd; - - pdev = vgadev->pdev; - pci_read_config_word(pdev, PCI_COMMAND, &cmd); - if (cmd & (PCI_COMMAND_IO | PCI_COMMAND_MEMORY)) { - found = pdev; - if (vga_arb_integrated_gpu(dev)) - break; - } - } - } - - if (found) { - vgaarb_info(&found->dev, "setting as boot device (VGA legacy resources not available)\n"); - vga_set_default_device(found); - return; - } - if (!vga_default_device()) { vgadev = list_first_entry_or_null(&vga_list, struct vga_device, list);