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

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Message-Id: <20251027063606.7962-1-Chloe_Chen@asmedia.com.tw>
Date: Mon, 27 Oct 2025 14:36:06 +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 23, 2025 at 04:51PM, Andy Shevchenko wrote:
> On Thu, Oct 23, 2025 at 04:04:55PM +0800, Szuying Chen wrote:
> > 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?
> > > 
> > 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.
> 
> We have such devices in many platforms, older ones use MFD framework with
> specific flag set, you may check how it's done there. But for this change is
> definitely NAK, take your time to find proper solution (see above for the
> hint).
> 
> 
> -- 
> With Best Regards,
> Andy Shevchenko

Hi Andy & Gregory,

Thanks for your feedback.
I will investigate the proper solution as you suggested.

Best Regards,
Chloe