linux-kernel - Re: [PATCH v5 0/3] Introduce Bandwidth OPPs for interconnects

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Date:   Thu, 15 Aug 2019 19:19:44 +0300
From:   Georgi Djakov <georgi.djakov@...aro.org>
To:     Saravana Kannan <saravanak@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Stephen Boyd <sboyd@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     vincent.guittot@...aro.org, seansw@....qualcomm.com,
        daidavid1@...eaurora.org, adharmap@...eaurora.org,
        Rajendra Nayak <rnayak@...eaurora.org>, sibis@...eaurora.org,
        bjorn.andersson@...aro.org, evgreen@...omium.org,
        kernel-team@...roid.com, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/3] Introduce Bandwidth OPPs for interconnects

Hi,

On 8/8/19 01:31, Saravana Kannan wrote:
> Interconnects and interconnect paths quantify their performance levels in
> terms of bandwidth and not in terms of frequency. So similar to how we have
> frequency based OPP tables in DT and in the OPP framework, we need
> bandwidth OPP table support in DT and in the OPP framework.
> 
> So with the DT bindings added in this patch series, the DT for a GPU
> that does bandwidth voting from GPU to Cache and GPU to DDR would look
> something like this:
> 
> gpu_cache_opp_table: gpu_cache_opp_table {
> 	compatible = "operating-points-v2";
> 
> 	gpu_cache_3000: opp-3000 {
> 		opp-peak-KBps = <3000000>;
> 		opp-avg-KBps = <1000000>;
> 	};
> 	gpu_cache_6000: opp-6000 {
> 		opp-peak-KBps = <6000000>;
> 		opp-avg-KBps = <2000000>;
> 	};
> 	gpu_cache_9000: opp-9000 {
> 		opp-peak-KBps = <9000000>;
> 		opp-avg-KBps = <9000000>;
> 	};
> };
> 
> gpu_ddr_opp_table: gpu_ddr_opp_table {
> 	compatible = "operating-points-v2";
> 
> 	gpu_ddr_1525: opp-1525 {
> 		opp-peak-KBps = <1525000>;
> 		opp-avg-KBps = <452000>;
> 	};
> 	gpu_ddr_3051: opp-3051 {
> 		opp-peak-KBps = <3051000>;
> 		opp-avg-KBps = <915000>;
> 	};
> 	gpu_ddr_7500: opp-7500 {
> 		opp-peak-KBps = <7500000>;
> 		opp-avg-KBps = <3000000>;
> 	};
> };
> 
> gpu_opp_table: gpu_opp_table {
> 	compatible = "operating-points-v2";
> 	opp-shared;
> 
> 	opp-200000000 {
> 		opp-hz = /bits/ 64 <200000000>;
> 	};
> 	opp-400000000 {
> 		opp-hz = /bits/ 64 <400000000>;
> 	};
> };
> 
> gpu@...4000 {
> 	...
> 	operating-points-v2 = <&gpu_opp_table>, <&gpu_cache_opp_table>, <&gpu_ddr_opp_table>;
> 	...
> };
> 
> v1 -> v3:
> - Lots of patch additions that were later dropped
> v3 -> v4:
> - Fixed typo bugs pointed out by Sibi.
> - Fixed bug that incorrectly reset rate to 0 all the time
> - Added units documentation
> - Dropped interconnect-opp-table property and related changes
> v4->v5:
> - Replaced KBps with kBps
> - Minor documentation fix
> 
> Cheers,
> Saravana
> 
> Saravana Kannan (3):
>   dt-bindings: opp: Introduce opp-peak-kBps and opp-avg-kBps bindings
>   OPP: Add support for bandwidth OPP tables
>   OPP: Add helper function for bandwidth OPP tables
> 
>  Documentation/devicetree/bindings/opp/opp.txt | 15 ++++--
>  .../devicetree/bindings/property-units.txt    |  4 ++
>  drivers/opp/core.c                            | 51 +++++++++++++++++++
>  drivers/opp/of.c                              | 41 +++++++++++----
>  drivers/opp/opp.h                             |  4 +-
>  include/linux/pm_opp.h                        | 19 +++++++
>  6 files changed, 121 insertions(+), 13 deletions(-)
> 

For the series:
Acked-by: Georgi Djakov <georgi.djakov@...aro.org>

Thanks,
Georgi