Re: [REGRESSION] no TPM device after "tpm_crb: Convert ACPI driver to a platform one"

Hi,

On 8/2/2026 2:54 PM, Julien wrote:
> Hello,
>
> Please keep in mind this is my first time reporting a Linux kernel 
> regression.
>
> Since commit 48fe2cddc85c ("tpm_crb: Convert ACPI driver to a platform 
> one"), my TPM device is no longer available. Both /dev/tpm0 and 
> /dev/tpmrm0 are missing.
>
> Log messages:
> platform MSFT0101:00: failed to claim resource 1: [mem 
> 0xfed40000-0xfed40fff]
> acpi MSFT0101:00: platform device creation failed: -16
>
So there's no platform device for the driver to bind to.

I think that these messages have been present in the kernel logs for 
quite some time, but previously they were not connected to any 
functional issues.


> I added some debug logging:
> ACPI resourcet[0] = [mem 0xfed40040-0xfed4103f flags 0x200]
> ACPI resourcet[1] = [mem 0xfed40000-0xfed40fff flags 0x200]
>
> I think the failure happens in kernel/resource.c: __insert_resource() 
> because of the two memory regions overlapping.
>
This is quite plausible, but if that's the case, it should be fixable.

Let me figure out something.


> I am attaching the TPM SSDT and the SDDT defining PTTB ACPI variable 
> address.
> The value of PPTB
> dd if=/dev/mem bs=1 skip=$((0x8AE5CFDC)) count=8 | hexdump -C
> 40 00 d4 fe 00 00 00 00
>
> Hardware information:
>   Manufacturer: Acer
>   Model: Aspire ES1-572
>   BIOS vendor: Insyde Corp.
>   BIOS version: V1.16
>   BIOS date: 09/18/2018
>
> Thanks
>
> #regzbot introduced: 48fe2cddc85c
>