linux-kernel - Re: [PATCH] kernel: resourse: Add conditional handling for ACPI device

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Message-Id: <20251023080455.19443-1-Chloe_Chen@asmedia.com.tw>
Date: Thu, 23 Oct 2025 16:04:55 +0800
From: Szuying Chen <chensiying21@...il.com>
To: akpm@...ux-foundation.org,
	andriy.shevchenko@...ux.intel.com,
	dan.j.williams@...el.com,
	gourry@...rry.net,
	jhubbard@...dia.com,
	akinobu.mita@...il.com,
	sumanthk@...ux.ibm.com,
	peterz@...radead.org,
	huang.ying.caritas@...il.com,
	linux-kernel@...r.kernel.org
Cc: Andrew_Su@...edia.com.tw,
	Yd_Tseng@...edia.com.tw,
	Ed_Huang@...edia.com.tw,
	Cindy1_Hsu@...edia.com.tw,
	Jesse1_Chang@...edia.com.tw,
	Richard_Hsu@...edia.com.tw,
	Chloe_Chen@...edia.com.tw
Subject: Re: [PATCH] kernel: resourse: Add conditional handling for ACPI device

On Sun, Oct 19, 2025 at 03:07AM, Andy Shevchenko wrote:
> On Fri, Oct 17, 2025 at 10:35:31AM +0800, Szuying Chen wrote:
> > To avoid address conflicts and related errors, specific checks for
> > the ACPI device "AMDIF031" should be bypassed.
> 
> TL;DR: NAK.
> 
> No, this is not how we should do the quirks (besides the use of CamelCase).
> Also, please provide more info why firmware may not be fixed properly at
> the same time, so we won't need this on an updated version?
> 
> -- 
> With Best Regards,
> Andy Shevchenko

The ACPI device AMDIF031 is a virtual (non-PCI) device located on the PCI
upstream port. Its memory resource is assigned by the BIOS within the bridge
windows of the PCI upstream port.

When the kernel creates ACPI/AMDIF031 and verifies memory resources, it may
detect an address conflict between AMDIF031 and the PCI upstream port. The
kernel then attempts to reassign resources for the PCI upstream port tree,
causing AMDIF031's memory resource to fall outside the bridge windows. This
makes the device inaccessible.

To prevent this and allow AMDIF031 to use the BIOS-assigned memory range,
skip resource reallocation when an address conflict is detected for this 
device.

Thanks
Chloe