linux-kernel - Re: [PATCH v4 0/11] Introduce a unified API for SCMI Server testing

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Message-ID: <fc09a68c-bd6d-0328-4052-88d40b50077d@gmail.com>
Date:   Fri, 28 Oct 2022 19:38:25 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Cristian Marussi <cristian.marussi@....com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     sudeep.holla@....com, james.quinlan@...adcom.com,
        Jonathan.Cameron@...wei.com, etienne.carriere@...aro.org,
        vincent.guittot@...aro.org, souvik.chakravarty@....com,
        wleavitt@...vell.com, peter.hilber@...nsynergy.com,
        nicola.mazzucato@....com, tarek.el-sherbiny@....com,
        quic_kshivnan@...cinc.com
Subject: Re: [PATCH v4 0/11] Introduce a unified API for SCMI Server testing

Hi Christian,

On 10/19/2022 1:46 PM, Cristian Marussi wrote:
[snip]

> In V2 the runtime enable/disable switching capability has been removed
> (for now) since still not deemed to be stable/reliable enough: as a
> consequence when SCMI Raw support is compiled in, the regular SCMI stack
> drivers are now inhibited permanently for that Kernel.

For our platforms (ARCH_BRCMSTB) we would need to have the ability to 
start with the regular SCMI stack to satisfy if nothing else, all clock 
consumers otherwise it makes it fairly challenging for us to boot to a 
prompt as we purposely turn off all unnecessary peripherals to conserve 
power. We could introduce a "full on" mode to remove the clock provider 
dependency, but I suspect others on "real" silicon may suffer from the 
same short comings.

Once user-space is reached, I suppose we could find a way to unbind from 
all SCMI consumers, and/or ensure that runtime PM is disabled, cpufreq 
is in a governor that won't do any active frequency switching etc.

What do you think?
-- 
Florian