Re: [PATCH v5 09/10] dt-bindings: firmware: add arm,ras-cper

[Ahmed Tiba <ahmed.tiba@arm.com>]

On 29/05/2026 17:44, Jonathan Cameron wrote:
> On Fri, 29 May 2026 10:50:49 +0100
> Ahmed Tiba<ahmed.tiba@arm.com> wrote:
>>   .../devicetree/bindings/firmware/arm,ras-cper.yaml | 54 ++++++++++++++++++++++
>>   MAINTAINERS                                        |  5 ++
>>   2 files changed, 59 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/firmware/arm,ras-cper.yaml b/Documentation/devicetree/bindings/firmware/arm,ras-cper.yaml
>> new file mode 100644
>> index 000000000000..3d4de096093f
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/firmware/arm,ras-cper.yaml
>> @@ -0,0 +1,54 @@
>> +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
>> +%YAML 1.2
>> +---
>> +$id:http://devicetree.org/schemas/firmware/arm,ras-cper.yaml#
>> +$schema:http://devicetree.org/meta-schemas/core.yaml#
>> +
>> +title: Arm RAS CPER provider
>> +
>> +maintainers:
>> +  - Ahmed Tiba<ahmed.tiba@arm.com>
>> +
>> +description:
>> +  Arm Reliability, Availability and Serviceability (RAS) firmware can expose
>> +  a firmware-first CPER error source directly via DeviceTree. Firmware
>> +  provides the CPER Generic Error Status block and notifies the OS through
>> +  an interrupt.
> I'd like some spec references in here if possible.
I can add a reference to the UEFI CPER specification for the Generic
Error Status record format.

For the firmware-first DT description itself I do not have a more 
specific public reference to cite.

>> +
>> +properties:
>> +  compatible:
>> +    const: arm,ras-cper
>> +
>> +  memory-region:
>> +    minItems: 1
>> +    items:
>> +      - description:
>> +          CPER Generic Error Status block exposed by firmware.
>> +      - description:
>> +          Optional firmware-owned ack buffer used on platforms
>> +          where firmware needs an explicit "ack" handshake before overwriting
>> +          the CPER buffer. Firmware watches bit 0 and expects the OS to set it
>> +          once the current status block has been consumed.
> Does the arm spec really make this optional?  Can we constraint it to not be
> just to make our lives easier?  I've never been sure how you would actually
> make a working platform without the ack support.
I will update the binding to require both memory-region entries.

Best regards,
Ahmed