linux-kernel - Re: [RFC 0/2] Add support for SCMI QTI Memlat Vendor Protocol

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Date:   Thu, 3 Nov 2022 09:41:21 +0000
From:   Cristian Marussi <cristian.marussi@....com>
To:     Sibi Sankar <quic_sibis@...cinc.com>
Cc:     andersson@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        robh+dt@...nel.org, sudeep.holla@....com, agross@...nel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, konrad.dybcio@...ainline.org,
        quic_avajid@...cinc.com, souvik.chakravarty@....com
Subject: Re: [RFC 0/2] Add support for SCMI QTI Memlat Vendor Protocol

On Thu, Nov 03, 2022 at 10:28:30AM +0530, Sibi Sankar wrote:
> The patch series documents the bindings and adds support for the
> SCMI QTI memlat (memory latency) vendor protocol. The protocol takes
> in several tuneables including the IPM ratio (Instructions Per Miss),
> bus bandwidth requirements and PMU maps to enable frequency scaling
> of various buses (L3/LLCC/DDR). The scaling is performed by the HW
> memory latency governor running on the CPUSS Control Processor.
> 
> Depends on CPUCP mailbox driver:
> https://patchwork.kernel.org/project/linux-arm-msm/cover/1663135386-26270-1-git-send-email-quic_sibis@quicinc.com/
> 

[+ CC: souvik.chakravarty@....com ]

Hi Sibi,

Nice to see vendor protocols starting to make their way into upstream !

I only glanced through the series as of now, and I'd have a few
questions before going on with the review:

 - why this protocol is dependent on a specific transport ?
   Is it to compile it only on platform supoprting it without adding
   a per-protocol Kconfig ?

Protocols are anyway enumerated at SCMI stack probe time so even if it
is not there it just won't be activated...I maybe missing something.

Thanks,
Cristian