linux-kernel - Re: [PATCH v5 0/7] PM / devfreq: Use OPP interface to handle the frequency

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]

Date:   Mon, 6 Nov 2017 10:11:13 -0800
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Chanwoo Choi <cw00.choi@...sung.com>
Cc:     MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        rafael.j.wysocki@...el.com, chanwoo@...nel.org,
        inki.dae@...sung.com, lkml <linux-kernel@...r.kernel.org>,
        Linux PM list <linux-pm@...r.kernel.org>,
        Vinayak Holikatti <vinholikatti@...il.com>,
        Vivek Gautam <vivek.gautam@...eaurora.org>
Subject: Re: [PATCH v5 0/7] PM / devfreq: Use OPP interface to handle the frequency

On Sun, Oct 22, 2017 at 6:32 PM, Chanwoo Choi <cw00.choi@...sung.com> wrote:
> These patches makes the devfreq to use the OPP interface and clean-up codes.
>

Hi Chanwoo,

This patch series breaks UFS support on modern Qualcomm platforms
(e.g. MSM8996).

Prior to this series the call to devm_devfreq_add_device() would
return ok even though the ufshcd device does not come with a opp
table. Afaict the code then relies on the devfreq code to target 0 and
MAX_INT (see ufshcd_devfreq_target()), to switch between a "high" and
"low" frequency.

I'm quite skeptical of the ufshcd code, so can you please confirm if
this usage of the devfreq interface is valid or not?

PS. If I do register some frequencies (and hack up
ufshcd_devfreq_target() accordingly) this works again, but the "high"
and "low" currently affects two clocks with different frequencies, so
I'm not sure how to properly describe the two clocks frequencies.
Should I just map "high"/"low" of the primary clock to "high"/"low"
frequencies of the secondary clock?

Regards,
Bjorn