Re: acpi: Remove ETM from AMBA scan list (was Re: [PATCH V6 6/6] coresight: etm4x: Add ACPI support in platform driver)

[Steve Clevenger OS <scclevenger@os.amperecomputing.com>]

Hi Sudeep,

On 7/26/2023 8:03 AM, Sudeep Holla wrote:
> On Wed, Jul 26, 2023 at 04:33:26PM +0200, Rafael J. Wysocki wrote:
>> On Tue, Jul 25, 2023 at 10:18 PM Steve Clevenger OS
>> <scclevenger@os.amperecomputing.com> wrote:
>>>
>>>
>>> Hi Rafael, Len,
>>>
>>> On 7/24/2023 9:25 AM, Suzuki K Poulose wrote:
>>>> Hi Rafael/Len
>>>>
>>>> On 19/07/2023 11:11, Suzuki K Poulose wrote:
>>>>> Rafael, Len
>>>>>
>>>>> Ping (packets 6, lost 100%).
>>>>>
>>>>>
>>>>> On 10/07/2023 17:40, Suzuki K Poulose wrote:
>>>>>> Rafael, Len
>>>>>>
>>>>>> On 10/07/2023 07:25, Anshuman Khandual wrote:
>>>>>>> From: Suzuki K Poulose <suzuki.poulose@arm.com>
>>>>>>>
>>>>>>> Drop ETM4X ACPI ID from the AMBA ACPI device list, and instead just
>>>>>>> move it
>>>>>>> inside the new ACPI devices list detected and used via platform driver.
>>>>>>>
>>>>>>> Cc: "Rafael J. Wysocki" <rafael@kernel.org>
>>>>>>> Cc: Len Brown <lenb@kernel.org>
>>>>>>> Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
>>>>>>> Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
>>>>>>> Cc: Mike Leach <mike.leach@linaro.org>
>>>>>>> Cc: Leo Yan <leo.yan@linaro.org>
>>>>>>> Cc: Sudeep Holla <sudeep.holla@arm.com>
>>>>>>> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
>>>>>>> Cc: linux-acpi@vger.kernel.org
>>>>>>> Cc: coresight@lists.linaro.org
>>>>>>> Cc: linux-arm-kernel@lists.infradead.org
>>>>>>> Cc: linux-kernel@vger.kernel.org
>>>>>>> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> (for ACPI specific
>>>>>>> changes)
>>>>>>> Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
>>>>>>> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
>>>>>>
>>>>>> We would like to queue this via coresight tree. The acpi_amba bits have
>>>>>> been reviewed by Sudeep. Please could you give us an Ack, if you are
>>>>>> happy with the proposal ?
>>>>>>
>>>>
>>>> Please could one of you respond to this patch ? We are blocked on your
>>>> Ack for queuing this. There are machines out there, which rely on this
>>>> patch to use Arm self-hosted tracing based on CoreSight.
>>>>
>>>> Kind regards
>>>> Suzuki
>>>
>>> Ampere Computing AmpereOne machines rely on this patch series to enable
>>> System Register Access to the ETMv4. Ampere removed the ETM MMIO
>>> descriptions from our CoreSight ACPI to use this.
>>>
>>> Suzuki's e-mail requests for review/Ack of this patch thread date back
>>> to May 30.
>>
>> I've just talked to Suzuki about this:
>>
>> https://lore.kernel.org/linux-acpi/20230726140515.368981-1-suzuki.poulose@arm.com
>>
>> This patch has received a Reviewed-by from Sudeep which for all
>> purposes should be sufficient for any ARM-related ACPI material that
>> doesn't affect any other architectures.  An ACK from me (or Len for
>> that matter) would not make any real difference from the technical
>> perspective.
>>
>> I would appreciate assigning an official ARM maintainer to acpi_amba.c
>> so as to avoid such unnecessary delays in the future.
> 
> Ah I just crossed and replied on other thread. I will soon send an update
> to add this file under Arm ACPI for the maintenance.
> 

Thank you.

Steve C.