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Re: [PATCH v2 2/5] dt-bindings: gpu: add a power_model optional properties for MALI

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On Mon, Jul 17, 2017 at 04:14:28PM +0800, Caesar Wang wrote:
> This patch adds the MALI's power-model to set the IPA model to be used
> for power management.

What's IPA? India Pale Ale or Intermediate Physical Address?

> 
> Signed-off-by: Caesar Wang <wxt@rock-chips.com>
> ---
> 
> Changes in v2: None
> 
>  Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt
> index a461e47..b616e6b 100644
> --- a/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt
> +++ b/Documentation/devicetree/bindings/gpu/arm,mali-midgard.txt
> @@ -37,6 +37,18 @@ Optional properties:
>  - operating-points-v2 : Refer to Documentation/devicetree/bindings/power/opp.txt
>    for details.
>  
> +- power_model : Sets power model parameters. Note that this model was designed for the Juno
> +	        platform, and may not be suitable for other platforms. A structure containing :
> +	- compatible: Should be arm,mali-simple-power-model
> +	- dynamic-coefficient: Coefficient, in pW/(Hz V^2), which is multiplied
> +	  by v^2*f to calculate the dynamic power consumption.
> +	- static-coefficient: Coefficient, in uW/V^3, which is multiplied by
> +	  v^3 to calculate the static power consumption.
> +	- ts: An array containing coefficients for the temperature scaling
> +	  factor. This is used to scale the static power by a factor of
> +	  tsf/1000000, where tsf = ts[3]*T^3 + ts[2]*T^2 + ts[1]*T + ts[0],
> +	  and T = temperature in degrees.
> +	- thermal-zone: A string identifying the thermal zone used for the GPU

This can all easily be implied by the compatible string. I'm not 
inclined to accept something Mali specific here.

This looks *very* precise, but I'd be surprised if these values are any 
more than magic values (at least the dynamic coef) adjusted until the 
desired power/performance requirements are achieved. To put it another 
way, why don't we have similar values for CPUs? 

Rob

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[PATCH v2 0/5] arm64: dts: rockchip: support mail and IPA thermal for rk3399 Caesar Wang <wxt@rock-chips.com> - 2017-07-17 10:20 +0200
  [PATCH v2 2/5] dt-bindings: gpu: add a power_model optional properties for MALI Caesar Wang <wxt@rock-chips.com> - 2017-07-17 10:20 +0200
    Re: [PATCH v2 2/5] dt-bindings: gpu: add a power_model optional  properties for MALI Rob Herring <robh@kernel.org> - 2017-07-17 22:10 +0200
      Re: [PATCH v2 2/5] dt-bindings: gpu: add a power_model optional  properties for MALI Caesar Wang <wxt@rock-chips.com> - 2017-07-18 03:00 +0200
  [PATCH v2 5/5] arm64: dts: rockchip: update the thermal zones for RK3399 SoCs Caesar Wang <wxt@rock-chips.com> - 2017-07-17 10:20 +0200
  [PATCH v2 4/5] arm64: dts: rockchip: enable the GPU for RK3399-GRU Caesar Wang <wxt@rock-chips.com> - 2017-07-17 10:20 +0200
  [PATCH v2 1/5] dt-bindings: gpu: add the RK3399 mali for rockchip specifics Caesar Wang <wxt@rock-chips.com> - 2017-07-17 10:20 +0200
    Re: [PATCH v2 1/5] dt-bindings: gpu: add the RK3399 mali for  rockchip specifics Rob Herring <robh@kernel.org> - 2017-07-17 22:00 +0200

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