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

From: Georgi Djakov <georgi.djakov@linaro.org>
To: Saravana Kannan <saravanak@google.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
	Stephen Boyd <sboyd@kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: vincent.guittot@linaro.org, seansw@qti.qualcomm.com,
	daidavid1@codeaurora.org, adharmap@codeaurora.org,
	Rajendra Nayak <rnayak@codeaurora.org>,
	sibis@codeaurora.org, bjorn.andersson@linaro.org,
	evgreen@chromium.org, kernel-team@android.com,
	linux-pm@vger.kernel.org, devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v5 0/3] Introduce Bandwidth OPPs for interconnects
Date: Thu, 15 Aug 2019 19:19:44 +0300	[thread overview]
Message-ID: <b8a6020f-eda5-0c3d-b365-a294c28b9650@linaro.org> (raw)
In-Reply-To: <20190807223111.230846-1-saravanak@google.com>

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@7864000 {
> 	...
> 	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@linaro.org>

Thanks,
Georgi