linux-kernel - Re: [PATCH 1/1] firmware: arm_scmi: Increase MAX

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Message-ID: <20251211-masterful-caterpillar-of-love-bc2d4c@sudeepholla>
Date: Thu, 11 Dec 2025 13:48:25 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: "Alexey Klimov" <alexey.klimov@...aro.org>
Cc: "Vivek Aknurwar" <vivek.aknurwar@....qualcomm.com>,
	<cristian.marussi@....com>, <linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-arm-msm@...r.kernel.org>, <mike.tipton@....qualcomm.com>
Subject: Re: [PATCH 1/1] firmware: arm_scmi: Increase MAX_OPPS to 64

On Thu, Dec 11, 2025 at 01:14:06PM +0000, Alexey Klimov wrote:
> > On 10/14/2025 12:34 AM, Vivek Aknurwar wrote:
> >> Some upcoming SoCs define more than 32 operating performance points (OPPs),
> >> exceeding the current SCMI protocol limit. Increase MAX_OPPS to 64
> >> (next power of 2) to support these configurations.
> 
> Didn't touch for a while. The way it is stated confuses me a bit.
> Should the value defined by protocol be updated out of the blue?
> Should the protocol (defined by spec) be changed first?
> 

Ah good point on confusing commit message. I just assumed it is limitation
of the implementation. I can update the log when applying. It is not spec
or protocol limitation for sure.

How about this ?

  | firmware: arm_scmi: Increase performance MAX_OPPS limit to 64
  |
  | Some platforms expose more than 32 operating performance points (OPPs)
  | per performance domain via the SCMI performance protocol, but the
  | driver currently limits the number of OPPs it can handle to 32 via
  | MAX_OPPS.
  |
  | Bump MAX_OPPS to 64 so that these platforms can register all their
  | performance levels. This is an internal limit in the driver only and
  | does not affect the SCMI protocol ABI.
  |
  | 64 is chosen as the next power of two above the existing limit.

-- 
Regards,
Sudeep