Messages in this thread | | | Subject | Re: [RFC PATCH 08/11] arm: dts: exynos: Add parents and #interconnect-cells to Exynos4412 | From | Artur Świgoń <> | Date | Wed, 31 Jul 2019 15:00:56 +0200 |
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On Wed, 2019-07-24 at 21:24 +0200, Krzysztof Kozlowski wrote: > On Tue, Jul 23, 2019 at 02:20:13PM +0200, Artur Świgoń wrote: > > This patch adds two fields tp the Exynos4412 DTS: > > tp->to
Fixed. Thanks for catching the typo :)
> > - parent: to declare connections between nodes that are not in a > > parent-child relation in devfreq; > > Is it a standard property? > The explanation needs some improvement... why are you adding parent to a > devices which are not child-parent?
This is not a standard property. I actually wanted to call it 'neighbor' at first. If you take a look at [1] and search for 'Exynos4x12', you will see that there are two power lines, and each has exactly one parent block (the rest are modelled in devfreq as its children). In [2], the parent of each child is indicated using the 'devfreq' property, e.g.,
&bus_display { devfreq = <&bus_leftbus>; status = "okay"; };
The single piece missing to make this topology a connected graph (for interconnect QoS purposes) is the 'parent' property I proposed in this patch. bus_leftbus is dependent on bus_dmc, therefore using the term 'parent' is justified IMHO.
The explanation could be improved by adding what Chanwoo Choi < cw00.choi@samsung.com> expressed in a parallel reply to this patch: > - If 'devfreq' property is used between buses, > it indicates that there are requirement of sharing of power line. > - If 'parent' property is used between buses, > it indicates that there are requirement of interconnect connection.
[1] Documentation/devicetree/bindings/devfreq/exynos-bus.txt [2] arch/arm/boot/dts/exynos4412-odroid-common.dtsi (subject of this patch)
Best regards, -- Artur Świgoń Samsung R&D Institute Poland Samsung Electronics
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