From nobody Tue Oct 7 22:38:27 2025 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id EBE7128C2DC; Sun, 6 Jul 2025 14:36:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751812607; cv=none; b=kFNLa8c0KMm4fDcvPES1CozCYZuwtwRfM3RlI01J4FH4e0em82wFoLtGdo3EdSGNbww7Mn6BLUsweLCFD6Ym/oappIDeceegKrzoBRf3lxAUhX9Bo//NF05OKquhpkhxa0jm7IRmZKa+hM4Vd+AF+xt5S6f2jblPBM7SvYkd5SU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751812607; c=relaxed/simple; bh=mA7SFMfHy8OinIxgtmu9yWbldbYt6k6q8NSeQegNnJA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rjwmW3d+zmb44h1qe9P7JWlotp93BpNvVkho1kl7iXDCgP5ksNWONugjnP2XiV73FO86YxyIqBQJhkNWNsx2vgFNCOagQMN4aUMkaqFDtQqIdcHHiaYRaO7UvwE5imtn54z8FbIcWEhyzLX84y8RcEWkUCyXD8rfkRYtV4Q4Z8U= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=sYVYeC+6; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="sYVYeC+6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7BA94C4CEF4; Sun, 6 Jul 2025 14:36:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1751812606; bh=mA7SFMfHy8OinIxgtmu9yWbldbYt6k6q8NSeQegNnJA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=sYVYeC+6e5OzGIchOu7GvaySxrAMZ+Bls0YeuisZup4XCUIRLsoBGtO+yoGMLuEbz BWzz0dfPhCzA6rCFKmi8QdDoeOhV3mmLqLskqGGhMFiVKHcEBvAvYWfBgNlI8N+fdI lpPH3flaG6PJJbHwr5ae62YYTCuxr5XkC2nLmfi0BP+InVH4+f3b9ETwE4p91f5LtX NXL01QEjUR0etWMbpJqif9KssgNkjfwwUywJYxEd6XRvZKTeMewbJbFfifB9L2wE1a IxlMW4hX3ZO+lWVzAAsGmTojyQt4cE9AOSC39/BlHNEPVXvwresJ6XINXMYLST9anZ 6cS53xc8Tkymg== From: Mario Limonciello To: David Airlie , Bjorn Helgaas Cc: Alex Deucher , =?UTF-8?q?Christian=20K=C3=B6nig?= , Simona Vetter , Lukas Wunner , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Woodhouse , Lu Baolu , Joerg Roedel , Will Deacon , Robin Murphy , Alex Williamson , Jaroslav Kysela , Takashi Iwai , dri-devel@lists.freedesktop.org (open list:DRM DRIVERS), linux-kernel@vger.kernel.org (open list), iommu@lists.linux.dev (open list:INTEL IOMMU (VT-d)), linux-pci@vger.kernel.org (open list:PCI SUBSYSTEM), kvm@vger.kernel.org (open list:VFIO DRIVER), linux-sound@vger.kernel.org (open list:SOUND), Daniel Dadap , Mario Limonciello Subject: [PATCH v7 9/9] PCI: Add a new 'boot_display' attribute Date: Sun, 6 Jul 2025 09:36:13 -0500 Message-ID: <20250706143613.1972252-10-superm1@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250706143613.1972252-1-superm1@kernel.org> References: <20250706143613.1972252-1-superm1@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Mario Limonciello On systems with multiple GPUs there can be uncertainty which GPU is the primary one used to drive the display at bootup. In order to disambiguate this add a new sysfs attribute 'boot_display' that uses the output of video_is_primary_device() to populate whether a PCI device was used for driving the display. Reviewed-by: Thomas Zimmermann Signed-off-by: Mario Limonciello --- v7: * fix lkp failure * Add tag v6: * Only show for the device that is boot display * Only create after PCI device sysfs files are initialized to ensure that resources are ready. v4: * new patch --- Documentation/ABI/testing/sysfs-bus-pci | 8 +++++ drivers/pci/pci-sysfs.c | 46 +++++++++++++++++++++++++ 2 files changed, 54 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/te= sting/sysfs-bus-pci index 69f952fffec72..8b455b1a58852 100644 --- a/Documentation/ABI/testing/sysfs-bus-pci +++ b/Documentation/ABI/testing/sysfs-bus-pci @@ -612,3 +612,11 @@ Description: =20 # ls doe_features 0001:01 0001:02 doe_discovery + +What: /sys/bus/pci/devices/.../boot_display +Date: October 2025 +Contact: Linux PCI developers +Description: + This file indicates the device was used as a boot + display. If the device was used as the boot display, the file + will be present and contain "1". diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c index 268c69daa4d57..6b1a0ae254d3a 100644 --- a/drivers/pci/pci-sysfs.c +++ b/drivers/pci/pci-sysfs.c @@ -30,6 +30,7 @@ #include #include #include +#include #include "pci.h" =20 #ifndef ARCH_PCI_DEV_GROUPS @@ -679,6 +680,13 @@ const struct attribute_group *pcibus_groups[] =3D { NULL, }; =20 +static ssize_t boot_display_show(struct device *dev, struct device_attribu= te *attr, + char *buf) +{ + return sysfs_emit(buf, "1\n"); +} +static DEVICE_ATTR_RO(boot_display); + static ssize_t boot_vga_show(struct device *dev, struct device_attribute *= attr, char *buf) { @@ -1051,6 +1059,37 @@ void pci_remove_legacy_files(struct pci_bus *b) } #endif /* HAVE_PCI_LEGACY */ =20 +/** + * pci_create_boot_display_file - create a file in sysfs for @dev + * @pdev: dev in question + * + * Creates a file `boot_display` in sysfs for the PCI device @pdev + * if it is the boot display device. + */ +static int pci_create_boot_display_file(struct pci_dev *pdev) +{ +#ifdef CONFIG_VIDEO + if (video_is_primary_device(&pdev->dev)) + return sysfs_create_file(&pdev->dev.kobj, &dev_attr_boot_display.attr); +#endif + return 0; +} + +/** + * pci_remove_boot_display_file - remove the boot display file for @dev + * @pdev: dev in question + * + * Removes the file `boot_display` in sysfs for the PCI device @pdev + * if it is the boot display device. + */ +static void pci_remove_boot_display_file(struct pci_dev *pdev) +{ +#ifdef CONFIG_VIDEO + if (video_is_primary_device(&pdev->dev)) + sysfs_remove_file(&pdev->dev.kobj, &dev_attr_boot_display.attr); +#endif +} + #if defined(HAVE_PCI_MMAP) || defined(ARCH_GENERIC_PCI_MMAP_RESOURCE) /** * pci_mmap_resource - map a PCI resource into user memory space @@ -1654,9 +1693,15 @@ static const struct attribute_group pci_dev_resource= _resize_group =3D { =20 int __must_check pci_create_sysfs_dev_files(struct pci_dev *pdev) { + int retval; + if (!sysfs_initialized) return -EACCES; =20 + retval =3D pci_create_boot_display_file(pdev); + if (retval) + return retval; + return pci_create_resource_files(pdev); } =20 @@ -1671,6 +1716,7 @@ void pci_remove_sysfs_dev_files(struct pci_dev *pdev) if (!sysfs_initialized) return; =20 + pci_remove_boot_display_file(pdev); pci_remove_resource_files(pdev); } =20 --=20 2.43.0