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From: Sibi Sankar <sibis@codeaurora.org>
To: Georgi Djakov <georgi.djakov@linaro.org>,
	vireshk@kernel.org, sboyd@kernel.org, nm@ti.com,
	robh+dt@kernel.org, mark.rutland@arm.com, rjw@rjwysocki.net
Cc: jcrouse@codeaurora.org, vincent.guittot@linaro.org,
	bjorn.andersson@linaro.org, amit.kucheria@linaro.org,
	seansw@qti.qualcomm.com, daidavid1@codeaurora.org,
	evgreen@chromium.org, linux-pm@vger.kernel.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH v2 1/5] dt-bindings: opp: Introduce bandwidth-MBps bindings
Date: Wed, 24 Apr 2019 14:14:29 +0530
Message-ID: <662bcd9c-abed-23d1-865b-220adfd95ab7@codeaurora.org> (raw)
In-Reply-To: <20190423132823.7915-2-georgi.djakov@linaro.org>

Hey Georgi,

On 4/23/19 6:58 PM, Georgi Djakov wrote:
> In addition to frequency and voltage, some devices may have bandwidth
> requirements for their interconnect throughput - for example a CPU
> or GPU may also need to increase or decrease their bandwidth to DDR
> memory based on the current operating performance point.
> 
> Extend the OPP tables with additional property to describe the bandwidth
> needs of a device. The average and peak bandwidth values depend on the
> hardware and its properties.
> 
> Signed-off-by: Georgi Djakov <georgi.djakov@linaro.org>
> ---
>   Documentation/devicetree/bindings/opp/opp.txt | 38 +++++++++++++++++++
>   .../devicetree/bindings/property-units.txt    |  4 ++
>   2 files changed, 42 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> index 76b6c79604a5..830f0206aea7 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -132,6 +132,9 @@ Optional properties:
>   - opp-level: A value representing the performance level of the device,
>     expressed as a 32-bit integer.
>   
> +- bandwidth-MBps: The interconnect bandwidth is specified with an array containing
> +  the two integer values for average and peak bandwidth in megabytes per second.
> +
>   - clock-latency-ns: Specifies the maximum possible transition latency (in
>     nanoseconds) for switching to this OPP from any other OPP.
>   
> @@ -546,3 +549,38 @@ Example 6: opp-microvolt-<name>, opp-microamp-<name>:
>   		};
>   	};
>   };
> +
> +Example 7: bandwidth-MBps:
> +Average and peak bandwidth values for the interconnects between CPU and DDR
> +memory and also between CPU and L3 are defined per each OPP. Bandwidth of both
> +interconnects is scaled together with CPU frequency.
> +
> +/ {
> +	cpus {
> +		CPU0: cpu@0 {
> +			compatible = "arm,cortex-a53", "arm,armv8";
> +			...
> +			operating-points-v2 = <&cpu_opp_table>;
> +			/* path between CPU and DDR memory and CPU and L3 */
> +			interconnects = <&noc MASTER_CPU &noc SLAVE_DDR>,
> +					<&noc MASTER_CPU &noc SLAVE_L3>;
> +		};
> +	};
> +
> +	cpu_opp_table: cpu_opp_table {
> +		compatible = "operating-points-v2";
> +		opp-shared;
> +
> +		opp-200000000 {
> +			opp-hz = /bits/ 64 <200000000>;
> +			/* CPU<->DDR bandwidth: 457 MB/s average, 1525 MB/s peak */
> +			 * CPU<->L3 bandwidth: 914 MB/s average, 3050 MB/s peak */
> +			bandwidth-MBps = <457 1525>, <914 3050>;
> +		};
> +		opp-400000000 {
> +			opp-hz = /bits/ 64 <400000000>;
> +			/* CPU<->DDR bandwidth: 915 MB/s average, 3051 MB/s peak */
> +			 * CPU<->L3 bandwidth: 1828 MB/s average, 6102 MB/s peak */
> +			bandwidth-MBps = <915 3051>, <1828 6102>;
> +		};
> +	};

nit: missed closing braces

> diff --git a/Documentation/devicetree/bindings/property-units.txt b/Documentation/devicetree/bindings/property-units.txt
> index bfd33734faca..9c3dbefcdae8 100644
> --- a/Documentation/devicetree/bindings/property-units.txt
> +++ b/Documentation/devicetree/bindings/property-units.txt
> @@ -41,3 +41,7 @@ Temperature
>   Pressure
>   ----------------------------------------
>   -kpascal	: kiloPascal
> +
> +Throughput
> +----------------------------------------
> +-MBps		: megabytes per second
> 

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

  parent reply index

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-23 13:28 [PATCH v2 0/5] Introduce OPP bandwidth bindings Georgi Djakov
2019-04-23 13:28 ` [PATCH v2 1/5] dt-bindings: opp: Introduce bandwidth-MBps bindings Georgi Djakov
2019-04-24  5:33   ` Viresh Kumar
2019-04-24  6:46   ` Rajendra Nayak
2019-04-24  6:49     ` Viresh Kumar
2019-04-24  9:00       ` Sibi Sankar
2019-04-24  9:05         ` Viresh Kumar
2019-04-25  4:24         ` Bjorn Andersson
2019-04-24  8:44   ` Sibi Sankar [this message]
2019-04-23 13:28 ` [PATCH v2 2/5] interconnect: Add of_icc_get_by_index() helper function Georgi Djakov
2019-05-07 11:59   ` Sibi Sankar
2019-06-27  5:56     ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 3/5] OPP: Add support for parsing the interconnect bandwidth Georgi Djakov
2019-04-24  5:52   ` Viresh Kumar
2019-06-27  6:27     ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 4/5] OPP: Update the bandwidth on OPP frequency changes Georgi Djakov
2019-04-24  5:55   ` Viresh Kumar
2019-04-24 10:05   ` Sibi Sankar
2019-04-23 13:28 ` [PATCH v2 5/5] cpufreq: dt: Add support for interconnect bandwidth scaling Georgi Djakov
2019-06-01  2:12 ` [PATCH v2 0/5] Introduce OPP bandwidth bindings Saravana Kannan
2019-06-03 15:56   ` Jordan Crouse
2019-06-03 19:12     ` Saravana Kannan

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