linux-kernel - Re: [PATCH v7 1/7] dt-bindings: opp: Introduce opp-peak-kBps and opp-avg-kBps bindings

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Message-ID: <20200430050918.b2g2yc7xhvbzeqqq@vireshk-i7>
Date:   Thu, 30 Apr 2020 10:39:18 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Georgi Djakov <georgi.djakov@...aro.org>
Cc:     vireshk@...nel.org, nm@...com, sboyd@...nel.org,
        robh+dt@...nel.org, rjw@...ysocki.net, saravanak@...gle.com,
        sibis@...eaurora.org, rnayak@...eaurora.org,
        bjorn.andersson@...aro.org, vincent.guittot@...aro.org,
        jcrouse@...eaurora.org, evgreen@...omium.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 1/7] dt-bindings: opp: Introduce opp-peak-kBps and
 opp-avg-kBps bindings

On 24-04-20, 18:53, Georgi Djakov wrote:
> From: Saravana Kannan <saravanak@...gle.com>
> 
> Interconnects often quantify their performance points in terms of
> bandwidth. So, add opp-peak-kBps (required) and opp-avg-kBps (optional) to
> allow specifying Bandwidth OPP tables in DT.
> 
> opp-peak-kBps is a required property that replaces opp-hz for Bandwidth OPP
> tables.
> 
> opp-avg-kBps is an optional property that can be used in Bandwidth OPP
> tables.
> 
> Signed-off-by: Saravana Kannan <saravanak@...gle.com>
> Signed-off-by: Georgi Djakov <georgi.djakov@...aro.org>
> ---
> v7:
> * I have dropped Rob's Reviewed-by, because of the minor change below:
> * In order to store the bandwidth values for multiple paths, the
> opp-peak-kBps and opp-avg-kBps are now defined as arrays of integers,
> instead of just integers.
> * Improved wording (Viresh)
> 
> v6: https://lore.kernel.org/r/20191207002424.201796-2-saravanak@google.com
> 
>  Documentation/devicetree/bindings/opp/opp.txt | 20 ++++++++++++++++---
>  .../devicetree/bindings/property-units.txt    |  4 ++++
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> index 68592271461f..a8a6a3bfcfcb 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -83,9 +83,17 @@ properties.
>  
>  Required properties:
>  - opp-hz: Frequency in Hz, expressed as a 64-bit big-endian integer. This is a
> -  required property for all device nodes but devices like power domains. The
> -  power domain nodes must have another (implementation dependent) property which
> -  uniquely identifies the OPP nodes.
> +  required property for all device nodes except for devices like power domains
> +  or bandwidth opp tables. The devices which don't have this property must have

bandwidth opp table ?

> +  another (implementation dependent) property which uniquely identifies the OPP
> +  nodes.
> +
> +
> +- opp-peak-kBps: Peak bandwidth in kilobytes per second, expressed as an array
> +  of 32-bit big-endian integers. Each element of the array represents the
> +  peak bandwidth value of each interconnect path. The number of elements should
> +  match the number of interconnect paths. This is a required property for
> +  bandwidth OPP tables.
>  
>  Optional properties:
>  - opp-microvolt: voltage in micro Volts.
> @@ -132,6 +140,12 @@ Optional properties:
>  - opp-level: A value representing the performance level of the device,
>    expressed as a 32-bit integer.
>  
> +- opp-avg-kBps: Average bandwidth in kilobytes per second, expressed as an array
> +  of 32-bit big-endian integers. Each element of the array represents the
> +  average bandwidth value of each interconnect path. The number of elements
> +  should match the number of interconnect paths. This property is only
> +  meaningful in OPP tables where opp-peak-kBps is present.
> +
>  - clock-latency-ns: Specifies the maximum possible transition latency (in
>    nanoseconds) for switching to this OPP from any other OPP.
>  
> diff --git a/Documentation/devicetree/bindings/property-units.txt b/Documentation/devicetree/bindings/property-units.txt
> index e9b8360b3288..c80a110c1e26 100644
> --- a/Documentation/devicetree/bindings/property-units.txt
> +++ b/Documentation/devicetree/bindings/property-units.txt
> @@ -41,3 +41,7 @@ Temperature
>  Pressure
>  ----------------------------------------
>  -kpascal	: kilopascal
> +
> +Throughput
> +----------------------------------------
> +-kBps		: kilobytes per second

-- 
viresh