linux-kernel - Re: [PATCH v5 7/9] PCI/VGA: Replace vga_is_firmware

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Message-ID: <20250626204540.GA1639372@bhelgaas>
Date: Thu, 26 Jun 2025 15:45:40 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Mario Limonciello <superm1@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
	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>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	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 v5 7/9] PCI/VGA: Replace vga_is_firmware_default() with a
 screen info check

On Tue, Jun 24, 2025 at 03:30:40PM -0500, Mario Limonciello wrote:
> From: Mario Limonciello <mario.limonciello@....com>
> 
> vga_is_firmware_default() checks firmware resources to find the owner
> framebuffer resources to find the firmware PCI device.  This is an
> open coded implementation of screen_info_pci_dev().  Switch to using
> screen_info_pci_dev() instead.
> 
> Suggested-by: Thomas Zimmermann <tzimmermann@...e.de>
> Signed-off-by: Mario Limonciello <mario.limonciello@....com>

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

(after the kernel robot issue is fixed, of course)

> ---
> v5:
>  * split from next patch
> ---
>  drivers/pci/vgaarb.c | 29 ++---------------------------
>  1 file changed, 2 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/pci/vgaarb.c b/drivers/pci/vgaarb.c
> index 78748e8d2dbae..c3457708c01e3 100644
> --- a/drivers/pci/vgaarb.c
> +++ b/drivers/pci/vgaarb.c
> @@ -556,34 +556,9 @@ EXPORT_SYMBOL(vga_put);
>  
>  static bool vga_is_firmware_default(struct pci_dev *pdev)
>  {
> -#if defined(CONFIG_X86)
> -	u64 base = screen_info.lfb_base;
> -	u64 size = screen_info.lfb_size;
> -	struct resource *r;
> -	u64 limit;
> +	struct screen_info *si = &screen_info;
>  
> -	/* Select the device owning the boot framebuffer if there is one */
> -
> -	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
> -		base |= (u64)screen_info.ext_lfb_base << 32;
> -
> -	limit = base + size;
> -
> -	/* Does firmware framebuffer belong to us? */
> -	pci_dev_for_each_resource(pdev, r) {
> -		if (resource_type(r) != IORESOURCE_MEM)
> -			continue;
> -
> -		if (!r->start || !r->end)
> -			continue;
> -
> -		if (base < r->start || limit >= r->end)
> -			continue;
> -
> -		return true;
> -	}
> -#endif
> -	return false;
> +	return pdev == screen_info_pci_dev(si);
>  }
>  
>  static bool vga_arb_integrated_gpu(struct device *dev)
> -- 
> 2.43.0
>