linux-kernel - Re: [PATCH v2 0/9] Exynos Adaptive Supply Voltage support

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:   Wed, 24 Jul 2019 15:10:39 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Viresh Kumar <viresh.kumar@...aro.org>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>
Cc:     krzk@...nel.org, robh+dt@...nel.org, vireshk@...nel.org,
        devicetree@...r.kernel.org, kgene@...nel.org,
        pankaj.dubey@...sung.com, linux-samsung-soc@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, b.zolnierkie@...sung.com
Subject: Re: [PATCH v2 0/9] Exynos Adaptive Supply Voltage support

Hi Viresh,

On 2019-07-23 04:04, Viresh Kumar wrote:
> On 18-07-19, 16:30, Sylwester Nawrocki wrote:
>> This is second iteration of patch series adding ASV (Adaptive Supply
>> Voltage) support for Exynos SoCs. The first one can be found at:
>> https://lore.kernel.org/lkml/20190404171735.12815-1-s.nawrocki@samsung.com
>>
>> The main changes comparing to the first (RFC) version are:
>>   - moving ASV data tables from DT to the driver,
>>   - converting the chipid and the ASV drivers to use regmap,
>>   - converting the ASV driver to proper platform driver.
>>
>> I tried the opp-supported-hw bitmask approach as in the Qualcomm CPUFreq
>> DT bindings but it resulted in too many OPPs and DT nodes, around 200
>> per CPU cluster. So the ASV OPP tables are now in the ASV driver, as in
>> downstream kernels.
> Hmm. Can you explain why do you have so many OPPs? How many
> frequencies do you actually support per cluster and what all varies
> per frequency based on hw ? How many hw version do u have ?

For big cores there are 20 frequencies (2100MHz .. 200MHz). Each SoC 
might belong to one of the 3 production 'sets' and each set contains 14 
so called 'asv groups', which assign the certain voltage values for each 
of those 20 frequencies (the lower asv group means lower voltage needed 
for given frequency).

> I am asking as the OPP core can be improved to support your case if
> possible. But I need to understand the problem first.


Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland