linux-kernel - Re: [RFC v3 00/10] DDR/L3 Scaling support on SDM845 and SC7180 SoCs

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Date:   Wed, 29 Jan 2020 19:51:59 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     Viresh Kumar <viresh.kumar@...aro.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Georgi Djakov <georgi.djakov@...aro.org>, saravanak@...gle.com,
        "Menon, Nishanth" <nm@...com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Andy Gross <agross@...nel.org>,
        David Brown <david.brown@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Rafael Wysocki <rjw@...ysocki.net>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Douglas Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Amit Kucheria <amit.kucheria@...aro.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Jordan Crouse <jcrouse@...eaurora.org>,
        Sharat Masetty <smasetty@...eaurora.org>,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [RFC v3 00/10] DDR/L3 Scaling support on SDM845 and SC7180 SoCs

Hey Rob,

On 2020-01-29 08:24, Rob Clark wrote:
> On Mon, Jan 27, 2020 at 12:05 PM Sibi Sankar <sibis@...eaurora.org> 
> wrote:
>> 
>> This RFC series aims to extend cpu based scaling support to L3/DDR on
>> SDM845 and SC7180 SoCs.
>> 
>> Patches [1-3] - Blacklist SDM845 and SC7180 in cpufreq-dt-platdev
>> Patches [5-7] - Hack in a way to add/remove multiple opp tables to
>>                 a single device. I am yet to fix the debugfs to
>>                 support multiple opp_tables per device but wanted to
>>                 send what was working upstream to get an idea if 
>> multiple
>>                 opp tables per device is a feature that will be useful
>>                 upstream.
>> Patches [9-10] - Add the cpu/cpu-ddr/cpu-l3 opp tables for SDM845
>>                  and SC7180 SoCs.
>> 
>> v3:
>>  * Migrated to using Saravana's opp-kBps bindings [1]
>>  * Fixed some misc comments from Rajendra
>>  * Added support for SC7180
>> 
>> v2:
>>  * Incorporated Viresh's comments from:
>>  
>> https://lore.kernel.org/lkml/20190410102429.r6j6brm5kspmqxc3@vireshk-i7/
>>  
>> https://lore.kernel.org/lkml/20190410112516.gnh77jcwawvld6et@vireshk-i7/
>>  * Dropped cpufreq-map passive governor
>> 
>> Git-branch: https://github.com/QuinAsura/linux/tree/lnext-012420
>> 
>> Some alternate ways of hosting the opp-tables:
>> https://github.com/QuinAsura/linux/commit/50b92bfaadc8f9a0d1e12249646e018bd6d1a9d3
>> https://github.com/QuinAsura/linux/commit/3d23d1eefd16ae6d9e3ef91e93e78749d8844e98
>> Viresh didn't really like ^^ bindings and they dont really scale well. 
>> Just
>> including them here for completeness.
>> 
>> Depends on the following series:
>> [1] https://patchwork.kernel.org/cover/11277199/
>> [2] https://patchwork.kernel.org/cover/11055499/
>> [3] https://patchwork.kernel.org/cover/11326381/
> 
> So drive-by question, from the perspective of someone who cares about
> a non-cpu device that frequently enjoys a lot of bandwidth (ie. the
> GPU).. any thoughts on how ddr scaling would/should work for workloads
> where the CPU is not particularly busy?

I guess Jordan would have more info
about ^^. From what I can see from
the CAF trees there is a similar
device freq -> DDR Freq mapping that
you can achieve with required-opps
bindings and a custom governor ;)

> 
> BR,
> -R
> 
>> 
>> Sibi Sankar (10):
>>   arm64: dts: qcom: sdm845: Add SoC compatible to MTP
>>   cpufreq: blacklist SDM845 in cpufreq-dt-platdev
>>   cpufreq: blacklist SC7180 in cpufreq-dt-platdev
>>   OPP: Add and export helper to update voltage
>>   opp: of: export _opp_of_get_opp_desc_node
>>   opp: Allow multiple opp_tables to be mapped to a single device
>>   opp: Remove multiple attached opp tables from a device
>>   cpufreq: qcom: Update the bandwidth levels on frequency change
>>   arm64: dts: qcom: sdm845: Add cpu OPP tables
>>   arm64: dts: qcom: sc7180: Add cpu OPP tables
>> 
>>  arch/arm64/boot/dts/qcom/sc7180.dtsi    | 287 +++++++++++++++
>>  arch/arm64/boot/dts/qcom/sdm845-mtp.dts |   2 +-
>>  arch/arm64/boot/dts/qcom/sdm845.dtsi    | 453 
>> ++++++++++++++++++++++++
>>  drivers/cpufreq/cpufreq-dt-platdev.c    |   2 +
>>  drivers/cpufreq/qcom-cpufreq-hw.c       | 246 +++++++++++--
>>  drivers/opp/core.c                      | 111 +++++-
>>  drivers/opp/of.c                        |   3 +-
>>  drivers/opp/opp.h                       |   2 +
>>  include/linux/pm_opp.h                  |  10 +
>>  9 files changed, 1083 insertions(+), 33 deletions(-)
>> 
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora 
>> Forum,
>> a Linux Foundation Collaborative Project

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project.