linux-kernel - Re: [PATCH 1/2] arm64: tegra: add ACONNECT, ADMA and AGIC nodes

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Date:   Thu, 6 Jun 2019 08:06:57 +0100
From:   Jon Hunter <jonathanh@...dia.com>
To:     Sameer Pujar <spujar@...dia.com>, <thierry.reding@...il.com>,
        <robh+dt@...nel.org>, <mark.rutland@....com>
CC:     <devicetree@...r.kernel.org>, <linux-tegra@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] arm64: tegra: add ACONNECT, ADMA and AGIC nodes


On 06/06/2019 06:58, Sameer Pujar wrote:
> 
> On 6/4/2019 2:37 PM, Jon Hunter wrote:
>> On 06/05/2019 12:58, Sameer Pujar wrote:
>>> Add DT nodes for following devices on Tegra186 and Tegra194
>>>   * ACONNECT
>>>   * ADMA
>>>   * AGIC
>>>
>>> Signed-off-by: Sameer Pujar <spujar@...dia.com>
>>> ---
>>>   arch/arm64/boot/dts/nvidia/tegra186.dtsi | 67
>>> ++++++++++++++++++++++++++++++++
>>>   arch/arm64/boot/dts/nvidia/tegra194.dtsi | 67
>>> ++++++++++++++++++++++++++++++++
>>>   2 files changed, 134 insertions(+)
>>>
>>> diff --git a/arch/arm64/boot/dts/nvidia/tegra186.dtsi
>>> b/arch/arm64/boot/dts/nvidia/tegra186.dtsi
>>> index 6e2b6ce..2c432c9 100644
>>> --- a/arch/arm64/boot/dts/nvidia/tegra186.dtsi
>>> +++ b/arch/arm64/boot/dts/nvidia/tegra186.dtsi
>>> @@ -1153,4 +1153,71 @@
>>>                   (GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>;
>>>           interrupt-parent = <&gic>;
>>>       };
>>> +
>>> +    aconnect@...1000 {
>>> +        compatible = "nvidia,tegra210-aconnect";
>>> +        clocks = <&bpmp TEGRA186_CLK_APE>,
>>> +             <&bpmp TEGRA186_CLK_APB2APE>;
>>> +        clock-names = "ape", "apb2ape";
>>> +        power-domains = <&bpmp TEGRA186_POWER_DOMAIN_AUD>;
>>> +        #address-cells = <2>;
>>> +        #size-cells = <2>;
>>> +        ranges;
>> My recollection is that non-empty range is preferred from what Rob told
>> me in the past. See the Tegra210 binding.
> I see at various places empty ranges property is used. From DT spec, it
> means
> there is no translation in the address space between parent/child.

Yes that is correct, but this is what Rob told me in the past ...

"Use of non-empty ranges is preferred though there is not much benefit
if the parent and child sizes are the same. However, it does also
limit what is a valid address for those child nodes."

So I think it is best to be consistent.

> Also I looked at Tegra210 binding,
> ranges = <0x702c0000 0x0 0x702c0000 0x00040000>;
> Should it be encoded as a triplet(child addr, parent addr, length)?
Right but remember the parent address is 2 cells, hence the 4 values.

Jon

-- 
nvpublic