linux-kernel - Re: [PATCH v2 1/3] soc: qcom: ice: Add OPP-based clock scaling support for ICE

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <c04cd051-b6d0-4d98-ac2d-4fc7ffcb4301@oss.qualcomm.com>
Date: Fri, 21 Nov 2025 14:46:52 +0100
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Abhinaba Rakshit <abhinaba.rakshit@....qualcomm.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konradybcio@...nel.org>,
        Manivannan Sadhasivam <mani@...nel.org>,
        "James E.J. Bottomley" <James.Bottomley@...senPartnership.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Neeraj Soni <neeraj.soni@....qualcomm.com>
Cc: linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-scsi@...r.kernel.org
Subject: Re: [PATCH v2 1/3] soc: qcom: ice: Add OPP-based clock scaling
 support for ICE

On 11/21/25 11:36 AM, Abhinaba Rakshit wrote:
> Register optional operation-points-v2 table for ICE device
> and aquire its minimum and maximum frequency during ICE
> device probe.
> 
> Introduce clock scaling API qcom_ice_scale_clk which scale ICE
> core clock if valid (non-zero) frequencies are obtained from
> OPP-table. Zero min and max (default values) frequencies depicts
> clock scaling is disabled.
> 
> When an ICE-device specific OPP table is available, use the PM OPP
> framework to manage frequency scaling and maintain proper power-domain
> constraints. For legacy targets without an ICE-device specific OPP table,
> fall back to the standard clock framework APIs to set the frequency.

You can still set a frequency through OPP APIs if the table is empty
(and one is always created even if devm_pm_opp_of_add_table() fails)

[...]

>  	/*
>  	 * Legacy DT binding uses different clk names for each consumer,
> -	 * so lets try those first. If none of those are a match, it means
> -	 * the we only have one clock and it is part of the dedicated DT node.
> -	 * Also, enable the clock before we check what HW version the driver
> -	 * supports.
> +	 * so lets try those first. Also get its corresponding clock index.
> +	 */

I would argue *not* setting the rate on targets utilizing a binding without
an OPP table for the ICE is probably a smart thing to do, because we may
brownout the SoC this way

Konrad