From: Sudeep Holla <sudeep.holla@arm.com>
To: Ansuel Smith <ansuelsmth@gmail.com>
Cc: Rob Herring <robh+dt@kernel.org>, Andy Gross <agross@kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
MyungJoo Ham <myungjoo.ham@samsung.com>,
Kyungmin Park <kyungmin.park@samsung.com>,
Sudeep Holla <sudeep.holla@arm.com>,
Chanwoo Choi <cw00.choi@samsung.com>,
linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org,
linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: Re: [PATCH v2 1/2] devfreq: qcom: Add L2 Krait Cache devfreq scaling driver
Date: Wed, 30 Sep 2020 10:29:54 +0100 [thread overview]
Message-ID: <20200930092954.GA7125@bogus> (raw)
In-Reply-To: <20200929162926.139-1-ansuelsmth@gmail.com>
On Tue, Sep 29, 2020 at 06:29:24PM +0200, Ansuel Smith wrote:
> Qcom L2 Krait CPUs use the generic cpufreq-dt driver and doesn't actually
> scale the Cache frequency when the CPU frequency is changed. This
> devfreq driver register with the cpu notifier and scale the Cache
> based on the max Freq across all core as the CPU cache is shared across
> all of them. If provided this also scale the voltage of the regulator
> attached to the CPU cache. The scaling logic is based on the CPU freq
> and the 3 scaling interval are set by the device dts.
>
I have raised this concern before. I am worried this kind of independent
CPU and cache frequency controls make way for clkscrew kind of attacks.
Why can't the clocks be made parent/child or secondary and automatically
updated when CPU clocks are changed.
--
Regards,
Sudeep
next prev parent reply other threads:[~2020-09-30 9:31 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20200929162941epcas1p4a6f524f2406785934918c2a9f556ae4b@epcas1p4.samsung.com>
2020-09-29 16:29 ` [PATCH v2 1/2] devfreq: qcom: Add L2 Krait Cache devfreq scaling driver Ansuel Smith
2020-09-29 16:29 ` [PATCH v2 2/2] dt-bindings: arm: Document L2 Krait CPU Cache " Ansuel Smith
2020-09-30 9:29 ` Sudeep Holla [this message]
2020-09-30 11:56 ` [PATCH v2 1/2] devfreq: qcom: Add L2 Krait Cache devfreq " ansuelsmth
2020-09-30 13:57 ` Sudeep Holla
2020-09-30 15:21 ` ansuelsmth
2022-05-20 1:11 ` Chanwoo Choi
2022-05-20 0:52 ` Ansuel Smith
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