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 48F4EEEBB; Thu, 17 Jul 2025 20:56:59 +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=1752785820; cv=none; b=rDZQeg0DNFN7zEoctc+HgE7PYk4u3IG6MnZ71wzGTZ5wJEviF60wCHYv7vR97yj7zM8bxaaraeEFKNilHH9fARekm11k41gT0Ot+av3LUhImx93dmKM+X+jxhKCfsiqcpq2BuWflHsiiRVQ5WDj2yORq5uUPG9R1nTI+/BsActY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752785820; c=relaxed/simple; bh=hB3ECq2LvtFhlKyMHw+BjidxFJ+IC5vbDWpXnTL/FLU=; h=Date:From:To:Cc:Subject:Message-ID:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; b=ewvlJ4w0PnOlnpPb27kFPXTllNMQTbC09PT5gSItAaHxZoCB0dQ9koLWMhtg/u9uz/iS+XjKmZqS+x2M/4mfq3G2nQrF382lAy1r8MY/9gazEpKMTUWQD7dLlNtewmRcD5CD6nPDzAVl7dtk+YpNxk/b/v0iInbvWnUCcleZDDU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=nmPdFv9s; 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="nmPdFv9s" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9A0A7C4CEE3; Thu, 17 Jul 2025 20:56:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752785819; bh=hB3ECq2LvtFhlKyMHw+BjidxFJ+IC5vbDWpXnTL/FLU=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=nmPdFv9s4xlXAy1klUkoXPSEIZfqAtNu7pPXMsYZ+mkkqp7kW6roP3ESMsMkt0Tm0 sL7bQJ++QD5UvWMGMxt7cNCTr0sRD83lrrn6hnkyxBkvXEUubljBVW7FgmtDcrhGH0 nIDJO5CMCu1v2NUKcXj2djnP97ipb2+mtihiXNhZGRfQAAIAgNQZIUCpUeQPTeLW33 dXIt1V7/3Lnm/M2nXKSluFU5Rghb2HxuGVB8fPckOvJNGb26yYgDKZpsxme0YZN/no 8FBUx984WqoniDQvFrFm++xzhE49NoljTVZVgS8oVn0vv2p/Nxd1tslrTGk3D6XktK WcBSbB+Fg1GTA== Date: Thu, 17 Jul 2025 15:56:58 -0500 From: Bjorn Helgaas To: Mario Limonciello Cc: David Airlie , Bjorn Helgaas , Alex Deucher , Christian =?utf-8?B?S8O2bmln?= , 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 v9 0/9] Adjust fbcon console device detection Message-ID: <20250717205658.GA2654514@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: <20250717173812.3633478-1-superm1@kernel.org> On Thu, Jul 17, 2025 at 12:38:03PM -0500, Mario Limonciello wrote: > From: Mario Limonciello > > Systems with more than one GPU userspace doesn't know which one to be > used to treat as primary. The concept of primary is important to be > able to decide which GPU is used for display and which is used for > rendering. If it's guessed wrong then both GPUs will be kept awake > burning a lot of power. > > Historically it would use the "boot_vga" attribute but this isn't > present on modern GPUs. > > This series started out as changes to VGA arbiter to try to handle a case > of a system with 2 GPUs that are not VGA devices and avoid changes to > userspace. This was discussed but decided not to overload the VGA arbiter > for non VGA devices. > > Instead move the x86 specific detection of framebuffer resources into x86 > specific code that the fbcon can use to properly identify the primary > device. This code is still called from the VGA arbiter, and the logic does > not change there. To avoid regression default to VGA arbiter and only fall > back to looking up with x86 specific detection method. > > In order for userspace to also be able to discover which device was the > primary video display device create a new sysfs file 'boot_display'. > > A matching userspace implementation for this file is available here: > Link: https://gitlab.freedesktop.org/xorg/lib/libpciaccess/-/merge_requests/39 > Link: https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2038 > > Dave Airlie has been pinged for a comment on this approach. > Dave had suggested in the past [1]: > > " > But yes if that doesn't work, then maybe we need to make the boot_vga > flag mean boot_display_gpu, and fix it in the kernel > " > > This was one of the approached tried in earlier revisions and it was > rejected in favor of creating a new sysfs file (which is what this > version does). > > It is suggested that this series merge entirely through the PCI tree. > > Link: https://gitlab.freedesktop.org/xorg/lib/libpciaccess/-/merge_requests/37#note_2938602 [1] > > v9: > * Add more to cover letter > * Add bug link to last patch > * Update commit message for last patch > * Update boot_display documentation description > > Mario Limonciello (9): > PCI: Add helper for checking if a PCI device is a display controller > vfio/pci: Use pci_is_display() > vga_switcheroo: Use pci_is_display() > iommu/vt-d: Use pci_is_display() > ALSA: hda: Use pci_is_display() > Fix access to video_is_primary_device() when compiled without > CONFIG_VIDEO > PCI/VGA: Replace vga_is_firmware_default() with a screen info check > fbcon: Use screen info to find primary device > PCI: Add a new 'boot_display' attribute > > Documentation/ABI/testing/sysfs-bus-pci | 9 +++++ > arch/parisc/include/asm/video.h | 2 +- > arch/sparc/include/asm/video.h | 2 ++ > arch/x86/include/asm/video.h | 2 ++ > arch/x86/video/video-common.c | 17 ++++++++- > drivers/gpu/vga/vga_switcheroo.c | 2 +- > drivers/iommu/intel/iommu.c | 2 +- > drivers/pci/pci-sysfs.c | 46 +++++++++++++++++++++++++ > drivers/pci/vgaarb.c | 31 +++-------------- > drivers/vfio/pci/vfio_pci_igd.c | 3 +- > include/linux/pci.h | 15 ++++++++ > sound/hda/hdac_i915.c | 2 +- > sound/pci/hda/hda_intel.c | 4 +-- > 13 files changed, 102 insertions(+), 35 deletions(-) Applied to pci/boot-display for v6.17, thanks!