Re: [PATCH v6 10/10] arm_mpam: detect and enable MPAM-Fb PCC support

[Ben Horgan <ben.horgan@arm.com>]

Hi Andre,

On 7/31/26 09:16, Andre Przywara wrote:
> Hi Ben,
> 
> On 7/30/26 18:13, Ben Horgan wrote:
>> Hi Andre,
>>
>> On 7/30/26 16:25, Andre Przywara wrote:
>>> The Arm MPAM-Fb specification [1] describes a protocol to access MSC
>>> registers through a firmware interface. This requires a shared memory
>>> region to hold the message, and a mailbox to trigger the access.
>>> For ACPI this is wrapped as a PCC channel, described using existing
>>> ACPI abstractions.
>>>
>>> Add code to parse those PCC table descriptions associated with an MSC,
>>> and store the parsed information in the MSC struct.
>>> There can be multiple PCC channels, and each channel can serve multiple
>>> MSCs, so we need to keep track of the channel usage, using a list and
>>> a refcount.
>>>
>>> This will be used by the MPAM-Fb access wrapper code.
>>>
>>> [1] https://developer.arm.com/documentation/den0144/latest
>>>
>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>> Tested-by: Ritwick Sharma <ritwick.sharma@arm.com>
>> Ritwick gave his Tested-by for the series on v5. Any reason to just add the tag on this patch?
> 
> submitting-patches.rst says:
> "Both Tested-by and Reviewed-by tags, once received on mailing list from tester or reviewer, should
> be added by author to the *applicable* patches when sending next versions."
> 
> I think this system relies on MPAM-Fb, so he couldn't test each patch in isolation, but "just" that
> MPAM-Fb works, which is what only patch 10/10 enables.
> 
> So I find tags given for the whole series always tricky to handle, but in this case I figured patch
> 10/10 would be the right target.

Ok, yes. I agree with that principle - I'm still learning how these things are done. Perhaps patch 8
would have been relevant too.

Thanks,

Ben

> 
>> I guess patch 9 has significant enough changes to drop tags but I don't see it for the others.
> 
> Well, even smaller changes could ruin a whole thing, but IIUC in this case Ritwick's setup doesn't
> even enable error IRQs, so this part wasn't tested anyway.


> 
> Cheers,
> Andre.
>