From mboxrd@z Thu Jan 1 00:00:00 1970 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 625781DFFD; Thu, 26 Jun 2025 20:45:10 +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=1750970711; cv=none; b=fSrqmoyZziUgc3oZIR/6fSpbsuuTWVXb2WTklkpaVmeLTJOD4vlDN6uhjUUZqn5Mnk3oj3CGD0vJw5z+zc1xtPBaED0TkmC3qflcfsaYSVybexLlQbd+xuDbps03TdRxhMXJd8nkKXSoan+G9pgJA3M8KI7BuNY84rKAFaDrlls= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750970711; c=relaxed/simple; bh=CJ6mO3cr4jG1icSEY6xKaoG4NWir/iLdOPJzCFy9ROg=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=HSkPbp0P/Qv96iIoUDvBOcRzCTVt3cJqUnfrVngzR39Dlc228+HbVXupNPnE49ovGm5bgPeXOlCORVJOp7gH/qy8tOoC6NSBtKmermqTrLadWlxQ1Dq2CZ5OlDKqMY+TvS3n3qKi9/HJpqJfyb+7N8+yC9ndzGEjRCcVaFTX/9w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=WUQ9zz5g; 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="WUQ9zz5g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A8B9AC4CEEB; Thu, 26 Jun 2025 20:45:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750970709; bh=CJ6mO3cr4jG1icSEY6xKaoG4NWir/iLdOPJzCFy9ROg=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=WUQ9zz5g7kpLJsuM+EuDhq1O+g5v8A3acnpaVOuiYxV5U395klqrRxx9RdBm+KaJq AND/BD6VipRDukKwY5fWmT+HboXHtVDaK52s8rrpkM9+Ja6JB40RfkG2gFs7zxcu0I 2NROw2RUL5O1FWcK6cTURDsVJEQEjPuh9nJ6WG5KlrASpRJ7hQZuxsjmKI5MBZ93PU LDEnQDITbt7CsUx97NS6GWq6G/fXiC786idROJYUESnqEhTI51VgYWqSGHXnBK1F5p ovptNUqsYkDkl4Fl8HBH8fZvh268jXgUsBSk2qtGfpMgKskHENA9GAE0m2AjwN9RcF 5bBEDVjFKqEAQ== Date: Thu, 26 Jun 2025 15:45:08 -0500 From: Bjorn Helgaas To: Mario Limonciello Cc: Bjorn Helgaas , Alex Deucher , Christian =?utf-8?B?S8O2bmln?= , David Airlie , 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 , "open list:DRM DRIVERS" , open list , "open list:INTEL IOMMU (VT-d)" , "open list:PCI SUBSYSTEM" , "open list:VFIO DRIVER" , "open list:SOUND" , Daniel Dadap , Mario Limonciello Subject: Re: [PATCH v5 9/9] PCI: Add a new 'boot_display' attribute Message-ID: <20250626204508.GA1639269@bhelgaas> Precedence: bulk X-Mailing-List: linux-pci@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250624203042.1102346-10-superm1@kernel.org> On Tue, Jun 24, 2025 at 03:30:42PM -0500, Mario Limonciello wrote: > 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. > > Signed-off-by: Mario Limonciello Acked-by: Bjorn Helgaas Question below. > --- > v4: > * new patch > --- > Documentation/ABI/testing/sysfs-bus-pci | 9 +++++++++ > drivers/pci/pci-sysfs.c | 14 ++++++++++++++ > 2 files changed, 23 insertions(+) > > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci > index 69f952fffec72..897cfc1b0de0f 100644 > --- a/Documentation/ABI/testing/sysfs-bus-pci > +++ b/Documentation/ABI/testing/sysfs-bus-pci > @@ -612,3 +612,12 @@ Description: > > # 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 whether the device was used as a boot > + display. If the device was used as the boot display, the file > + will contain "1". If the device is a display device but wasn't > + used as a boot display, the file will contain "0". Is there a reason to expose this file if it wasn't a boot display device? Maybe it doesn't need to exist at all unless it contains "1"? > diff --git a/drivers/pci/pci-sysfs.c b/drivers/pci/pci-sysfs.c > index 268c69daa4d57..5bbf79b1b953d 100644 > --- a/drivers/pci/pci-sysfs.c > +++ b/drivers/pci/pci-sysfs.c > @@ -30,6 +30,7 @@ > #include > #include > #include > +#include > #include "pci.h" > > #ifndef ARCH_PCI_DEV_GROUPS > @@ -679,6 +680,13 @@ const struct attribute_group *pcibus_groups[] = { > NULL, > }; > > +static ssize_t boot_display_show(struct device *dev, struct device_attribute *attr, > + char *buf) > +{ > + return sysfs_emit(buf, "%u\n", video_is_primary_device(dev)); > +} > +static DEVICE_ATTR_RO(boot_display); > + > static ssize_t boot_vga_show(struct device *dev, struct device_attribute *attr, > char *buf) > { > @@ -1698,6 +1706,7 @@ late_initcall(pci_sysfs_init); > > static struct attribute *pci_dev_dev_attrs[] = { > &dev_attr_boot_vga.attr, > + &dev_attr_boot_display.attr, > NULL, > }; > > @@ -1710,6 +1719,11 @@ static umode_t pci_dev_attrs_are_visible(struct kobject *kobj, > if (a == &dev_attr_boot_vga.attr && pci_is_vga(pdev)) > return a->mode; > > +#ifdef CONFIG_VIDEO > + if (a == &dev_attr_boot_display.attr && pci_is_display(pdev)) > + return a->mode; > +#endif > + > return 0; > } > > -- > 2.43.0 >