linux-kernel - Re: [PATCH V2 2/5] PM / OPP: Add {opp-microvolt|opp-microamp|turbo-mode|opp-suspend}-<name> binding

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Message-ID: <20151105030245.GA20613@rob-hp-laptop>
Date:	Wed, 4 Nov 2015 21:02:45 -0600
From:	Rob Herring <robh@...nel.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>, robh+dt@...nel.org,
	sboyd@...eaurora.org, lee.jones@...aro.org,
	linaro-kernel@...ts.linaro.org, linux-pm@...r.kernel.org,
	mark.rutland@....com, pawel.moll@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org, nm@...com,
	devicetree@...r.kernel.org, b.zolnierkie@...sung.com,
	m.szyprowski@...sung.com, open list <linux-kernel@...r.kernel.org>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH V2 2/5] PM / OPP: Add
 {opp-microvolt|opp-microamp|turbo-mode|opp-suspend}-<name> binding

On Thu, Nov 05, 2015 at 07:11:53AM +0530, Viresh Kumar wrote:
> Depending on the version of hardware or its properties, which are only
> known at runtime, various properties of the OPP can change. For example,
> an OPP with frequency 1.2 GHz, may have different voltage/current
> requirements based on the version of the hardware it is running on.
> Similarly, it may or may not be a turbo or suspend OPP on those
> circumstances.
> 
> In order to not replicate the same OPP tables for varying values of all
> such fields, this commit introduces the concept of opp-property-<name>.
> The <name> can be chosen by the platform at runtime, and OPPs will be
> initialized depending on that name string. Currently support is extended
> for the following properties:
> - opp-microvolt-<name>
> - opp-microamp-<name>
> - turbo-mode-<name>
> - opp-suspend-<name>
> 
> If the name string isn't provided by the platform, or if it is provided
> but doesn't match the properties present in the OPP node, we will fall
> back to the original properties without the -<name> string, if they are
> available.
> 
> Reviewed-by: Stephen Boyd <sboyd@...eaurora.org>
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>
> ---
>  Documentation/devicetree/bindings/opp/opp.txt | 58 +++++++++++++++++++++++++++
>  1 file changed, 58 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/opp/opp.txt b/Documentation/devicetree/bindings/opp/opp.txt
> index d072fa0ffbd4..61c6f25cf8e2 100644
> --- a/Documentation/devicetree/bindings/opp/opp.txt
> +++ b/Documentation/devicetree/bindings/opp/opp.txt
> @@ -100,6 +100,14 @@ properties.
>    Entries for multiple regulators must be present in the same order as
>    regulators are specified in device's DT node.
>  
> +- opp-microvolt-<name>: Named opp-microvolt property. This is exactly similar to
> +  the above opp-microvolt property, but allows multiple voltage ranges to be
> +  provided for the same OPP. At runtime, the platform can pick a <name> and
> +  matching opp-microvolt-<name> property will be enabled for all OPPs. If the
> +  platform doesn't pick a specific <name> or the <name> doesn't match with any
> +  opp-microvolt-<name> properties, then opp-microvolt property shall be used, if
> +  present.
> +
>  - opp-microamp: The maximum current drawn by the device in microamperes
>    considering system specific parameters (such as transients, process, aging,
>    maximum operating temperature range etc.) as necessary. This may be used to
> @@ -112,6 +120,9 @@ properties.
>    for few regulators, then this should be marked as zero for them. If it isn't
>    required for any regulator, then this property need not be present.
>  
> +- opp-microamp-<name>: Named opp-microamp property. Similar to
> +  opp-microvolt-<name> property, but for microamp instead.
> +
>  - clock-latency-ns: Specifies the maximum possible transition latency (in
>    nanoseconds) for switching to this OPP from any other OPP.
>  
> @@ -120,9 +131,15 @@ properties.
>    frequency for a short duration of time limited by the device's power, current
>    and thermal limits.
>  
> +- turbo-mode-<name>: Named turbo-mode property. Similar to opp-microvolt-<name>
> +  property, but for turbo mode instead.
> +
>  - opp-suspend: Marks the OPP to be used during device suspend. Only one OPP in
>    the table should have this.
>  
> +- opp-suspend-<name>: Named opp-suspend property. Similar to
> +  opp-microvolt-<name> property, but for suspend opp instead.
> +

I don't think these last 2 make sense. turbo-mode is a flag that the 
mode has restrictions such as other cores have to be idle or something. 
Similarly, opp-suspend should not vary by <name>.

Rob
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