Re: [PATCH v2] ACPI: scan: Do not combine resources that overlap completely

[Jarkko Sakkinen <jarkko@kernel.org>]

On Sat, Aug 29, 2026 at 12:43:30AM +0200, Julien wrote:
> On Thu, Aug 20, 2026 at 9:11 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
> >
> > From: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
> >
> > Commit f234fdaae1ca ("ACPI: scan: Avoid registering platform devices
> > with resource overlaps") attempted to avoid platform device registration
> > errors due to overlaps of resources of the same type returned by the
> > same _CRS object in the ACPI tables.  It did that by combining two or
> > more overlapping resources into one, but it went too far and also
> > caused resources that overlap completely to be combined which broke
> > the arm-cmn driver that expects two MMIO resources to be present for
> > each device it binds to and it expects those two resources to overlap
> > completely.
> >
> > Address this issue by adding checks for completely overlapping
> > resources to acpi_platform_adjust_resources() and add a comment
> > explaining what is done there.
> >
> > Fixes: f234fdaae1ca ("ACPI: scan: Avoid registering platform devices with resource overlaps")
> > Reported-by: Nathan Chancellor <nathan@kernel.org>
> > Tested-by: Nathan Chancellor <nathan@kernel.org>
> > Closes: https://lore.kernel.org/linux-acpi/20260819003752.GA3063251@ax162/
> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > ---
> >
> > v1 -> v2:
> >    * It is better to check for complete overlaps both ways as suggested
> >      by Sashiko.
> >
> > @Julien: I would appreciate testing this on the machine that needed
> > commit f234fdaae1ca.
> >
> > ---
> >  drivers/acpi/acpi_platform.c |    8 +++++++-
> >  1 file changed, 7 insertions(+), 1 deletion(-)
> >
> > --- a/drivers/acpi/acpi_platform.c
> > +++ b/drivers/acpi/acpi_platform.c
> > @@ -85,7 +85,13 @@ static unsigned int acpi_platform_adjust
> >         for (i = 0; i < count; ) {
> >                 struct resource *res = &resources[i];
> >
> > -               if (resource_type(new_res) != resource_type(res) ||
> > +               /*
> > +                * Look for overlaps of resources of the same type that would
> > +                * cause resource insertion to fail down the road.
> > +                */
> > +               if (__resource_contains_unbound(res, new_res) ||
> > +                   __resource_contains_unbound(new_res, res) ||
> > +                   resource_type(new_res) != resource_type(res) ||
> >                     !resource_union(new_res, res, new_res)) {
> >                         i++;
> >                         continue;
> >
> >
> >
> 
> I have tested this on commit 1b78070aaef6. It seems the patch is
> already included in it.
> 
> TPM device still works. Here are the logs.
> acpi MSFT0101:00: [mem 0xfed40000-0xfed4103f] expanded due to overlap
> tpm_crb_acpi MSFT0101:00: [Firmware Bug]: Bad ACPI memory layout
> 
> If in the future if I need to make tests again, should I do them on
> the Linus Torvalds' branch?

What was the hardware where this happens?

Sorry, if I've ignored it (if it was mentioned previously).

BR, Jarkko