linux-kernel - Re: [PATCH v2 06/11] PCI: Fix restoring BARs on BAR resize rollback path

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Message-ID: <ec0f0db3-078a-4183-9791-84381befe1e2@amd.com>
Date: Fri, 14 Nov 2025 10:34:42 +0100
From: Christian König <christian.koenig@....com>
To: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Alex Bennée <alex.bennee@...aro.org>,
 Simon Richter <Simon.Richter@...yros.de>,
 Lucas De Marchi <lucas.demarchi@...el.com>,
 Alex Deucher <alexander.deucher@....com>, amd-gfx@...ts.freedesktop.org,
 Bjorn Helgaas <bhelgaas@...gle.com>, David Airlie <airlied@...il.com>,
 dri-devel@...ts.freedesktop.org, intel-gfx@...ts.freedesktop.org,
 intel-xe@...ts.freedesktop.org, Jani Nikula <jani.nikula@...ux.intel.com>,
 Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
 linux-pci@...r.kernel.org, Rodrigo Vivi <rodrigo.vivi@...el.com>,
 Simona Vetter <simona@...ll.ch>, Tvrtko Ursulin <tursulin@...ulin.net>,
 Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
 Michał Winiarski <michal.winiarski@...el.com>,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/11] PCI: Fix restoring BARs on BAR resize rollback
 path

Hi,

On 11/13/25 17:26, Ilpo Järvinen wrote:
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 7a899fb4de29..4e241836ae68 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -1736,7 +1736,7 @@ int amdgpu_device_resize_fb_bar(struct amdgpu_device *adev)
>  
>  	pci_release_resource(adev->pdev, 0);
>  
> -	r = pci_resize_resource(adev->pdev, 0, rbar_size);
> +	r = pci_resize_resource(adev->pdev, 0, rbar_size, 1 << 5);

It is HW generation specific if that is BAR 5 or 2 which needs protection.

There is an "if (adev->asic_type >= CHIP_BONAIRE) pci_release_resource(...);" which depends on the same criteria.

Something like this should work:

if (adev->asic_type >= CHIP_BONAIRE)
	r = pci_resize_resource(adev->pdev, 0, rbar_size, 1 << 5);
else
	r = pci_resize_resource(adev->pdev, 0, rbar_size, 1 << 2);

Apart from that the patch set looks really good to me and is certainly a very nice cleanup.

We can potentially also remove a bunch of the extra checks in amdgpu. Going to take care of it after this set landed.

Thanks,
Christian.

>  	if (r == -ENOSPC)
>  		dev_info(adev->dev,
>  			 "Not enough PCI address space for a large BAR.");