linux-kernel - Re: [PATCH v6 8/9] fbcon: Use screen info to find primary device

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Message-ID: <d8ca2ed5-5656-405b-bf30-defcbc20c619@suse.de>
Date: Fri, 27 Jun 2025 08:51:11 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Mario Limonciello <superm1@...nel.org>,
 Bjorn Helgaas <bhelgaas@...gle.com>
Cc: Alex Deucher <alexander.deucher@....com>,
 Christian König <christian.koenig@....com>,
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
 Lukas Wunner <lukas@...ner.de>,
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
 Maxime Ripard <mripard@...nel.org>, David Woodhouse <dwmw2@...radead.org>,
 Lu Baolu <baolu.lu@...ux.intel.com>, Joerg Roedel <joro@...tes.org>,
 Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
 Alex Williamson <alex.williamson@...hat.com>,
 Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
 "open list:DRM DRIVERS" <dri-devel@...ts.freedesktop.org>,
 open list <linux-kernel@...r.kernel.org>,
 "open list:INTEL IOMMU (VT-d)" <iommu@...ts.linux.dev>,
 "open list:PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
 "open list:VFIO DRIVER" <kvm@...r.kernel.org>,
 "open list:SOUND" <linux-sound@...r.kernel.org>,
 Daniel Dadap <ddadap@...dia.com>,
 Mario Limonciello <mario.limonciello@....com>
Subject: Re: [PATCH v6 8/9] fbcon: Use screen info to find primary device

Hi

Am 27.06.25 um 06:31 schrieb Mario Limonciello:
> From: Mario Limonciello <mario.limonciello@....com>
>
> On systems with non VGA GPUs fbcon can't find the primary GPU because
> video_is_primary_device() only checks the VGA arbiter.
>
> Add a screen info check to video_is_primary_device() so that callers
> can get accurate data on such systems.
>
> Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

Thanks for sticking with it. This patch is also useful without the sysfs 
interface.

Reviewed-by: Thomas Zimmermann <tzimmermann@...e.de>

Best regards
Thomas

> ---
> v5:
>   * Only change video-common.c
> v4:
>   * use helper
> ---
>   arch/x86/video/video-common.c | 13 ++++++++++++-
>   1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/video/video-common.c b/arch/x86/video/video-common.c
> index 81fc97a2a837a..917568e4d7fb1 100644
> --- a/arch/x86/video/video-common.c
> +++ b/arch/x86/video/video-common.c
> @@ -9,6 +9,7 @@
>   
>   #include <linux/module.h>
>   #include <linux/pci.h>
> +#include <linux/screen_info.h>
>   #include <linux/vgaarb.h>
>   
>   #include <asm/video.h>
> @@ -27,6 +28,7 @@ EXPORT_SYMBOL(pgprot_framebuffer);
>   
>   bool video_is_primary_device(struct device *dev)
>   {
> +	struct screen_info *si = &screen_info;
>   	struct pci_dev *pdev;
>   
>   	if (!dev_is_pci(dev))
> @@ -34,7 +36,16 @@ bool video_is_primary_device(struct device *dev)
>   
>   	pdev = to_pci_dev(dev);
>   
> -	return (pdev == vga_default_device());
> +	if (!pci_is_display(pdev))
> +		return false;
> +
> +	if (pdev == vga_default_device())
> +		return true;
> +
> +	if (pdev == screen_info_pci_dev(si))
> +		return true;
> +
> +	return false;
>   }
>   EXPORT_SYMBOL(video_is_primary_device);
>   

-- 
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)