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

On Thu, Aug 20, 2026 at 9:11 PM Rafael J. Wysocki <[email protected]> wrote:
>
> From: "Rafael J. Wysocki" <[email protected]>
>
> 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 <[email protected]>
> Tested-by: Nathan Chancellor <[email protected]>
> Closes: https://lore.kernel.org/linux-acpi/20260819003752.GA3063251@ax162/
> Signed-off-by: Rafael J. Wysocki <[email protected]>
> ---
>
> 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?