linux-kernel - Re: [PATCH v5 5/9] clk: qcom: apss-ipq6018: ipq5332: add safe source switch for a53pll

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

Message-ID: <b5033b2b-a39a-41d4-b47d-f120743a79bd@linaro.org>
Date:   Sat, 21 Oct 2023 19:04:54 +0200
From:   Konrad Dybcio <konrad.dybcio@...aro.org>
To:     Varadarajan Narayanan <quic_varada@...cinc.com>, agross@...nel.org,
        andersson@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        mturquette@...libre.com, sboyd@...nel.org, rafael@...nel.org,
        viresh.kumar@...aro.org, ilia.lin@...nel.org,
        sivaprak@...eaurora.org, quic_kathirav@...cinc.com,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v5 5/9] clk: qcom: apss-ipq6018: ipq5332: add safe source
 switch for a53pll



On 10/20/23 08:19, Varadarajan Narayanan wrote:
> Stromer Plus PLL found on IPQ53xx doesn't support dynamic
> frequency scaling. To achieve the same, we need to park the APPS
> PLL source to GPLL0, re configure the PLL and then switch the
> source to APSS_PLL_EARLY.
> 
> To support this, register a clock notifier to get the PRE_RATE
> and POST_RATE notification. Change the APSS PLL source to GPLL0
> when PRE_RATE notification is received, then configure the PLL
> and then change back the source to APSS_PLL_EARLY.
> 
> Additionally, not all SKUs of IPQ53xx support scaling. Hence,
> do the above to the SKUs that support scaling.
> 
> Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> Signed-off-by: Kathiravan T <quic_kathirav@...cinc.com>
> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> ---
This looks good, however I'm not sure if registering the callback
only on SoCs that are supposed to rate-change isn't
overly-defensive. That said, I'm not particularly against it.

Acked-by: Konrad Dybcio <konrad.dybcio@...aro.org>

Konrad