Re: [PATCH v2 2/4] firmware: arm_scmi: Add machine_allowlist and machine_blocklist

[Peng Fan <peng.fan@xxxxxxxxxxx>]

On Tue, Feb 11, 2025 at 03:46:36PM +0000, Sudeep Holla wrote:
>On Mon, Feb 10, 2025 at 01:19:14PM +0000, Peng Fan wrote:
>> 
>> I just have a prototype and tested on i.MX95.
>
>You didn't answer me @[1]. How can we disable it for perf/cpufreq if there
>are users already. I will look at the code once I am convince we can do that.
>For now, I am not. I am worried we may break some platform.

The only user in upstream kernel with using the dummy clock is juno-scmi.dtsi.

SCMI_PROTOCOL_PERF is used by two drivers cpufreq-scmi.c, scmi_perf_domain.c.

In cpufreq-scmi.c a dummy clock proviver is created, the gpu node in juno-scmi.dtsi
takes "<&scmi_dvfs 2>" into clocks property. I think this is wrong.

Why not use scmi_clk node? cpufreq created clk provider should only be limited
for cpu device which will not be impacted by fwdevlink.

If wanna to tune gpu performance, the power-domains property should be used,
not clocks property.

It is the juno-scmi.dtsi should be fixed.

If juno-scmi.dtsi will keep as it is, please suggest possible solution
on fixing the issue.

Regards,
Peng

>
>-- 
>Regards,
>Sudeep
>
>[1] https://lore.kernel.org/all/20241227151306.jh2oabc64xd54dms@bogus