linux-kernel - Re: [PATCH 2/5] arm64: dts: mediatek: cherry: Assign dp-intf aliases

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Date:   Mon, 24 Apr 2023 09:19:25 +0200
From:   AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...labora.com>
To:     Chen-Yu Tsai <wenst@...omium.org>
Cc:     matthias.bgg@...il.com, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, kernel@...labora.com
Subject: Re: [PATCH 2/5] arm64: dts: mediatek: cherry: Assign dp-intf aliases

Il 24/04/23 09:17, Chen-Yu Tsai ha scritto:
> On Mon, Apr 24, 2023 at 3:03 PM AngeloGioacchino Del Regno
> <angelogioacchino.delregno@...labora.com> wrote:
>>
>> Il 21/04/23 08:46, Chen-Yu Tsai ha scritto:
>>> On Thu, Apr 20, 2023 at 5:45 PM AngeloGioacchino Del Regno
>>> <angelogioacchino.delregno@...labora.com> wrote:
>>>>
>>>> On Cherry boards, the IP at 0x1c015000 (dp_intf0) is used as primary
>>>> dp-intf, while the other at 0x1c113000 (dp_intf1) is used as secondary:
>>>> assign them to dp-intf{0,1} aliases respectively.
>>>>
>>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>
>>>> ---
>>>>    arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 2 ++
>>>
>>> This should be applied at the SoC level. The display pipeline is fixed in
>>> MMSYS, so it applies to all MT8195 devices.
>>>
>>
>> It's fixed in the MMSYS configuration/driver but - as far as I remember (I can
>> recheck on the datasheets) - the dp_intfX function can be inverted meaning that
>> the MMSYS paths can be configured such that DP_INTF0 becomes secondary and the
>> other becomes primary: this is why I am putting that into mt8195-cherry and not
>> mt8195.dtsi.
> 
> Maybe that's possible, but the diagram in the datasheet suggests a fixed path.
> 
> Either way, it's not actually the problem. My original reply is probably
> inaccurate. AFAIK the aliases are used to identify the individual hardware
> blocks, which otherwise have the same compatible string. So the numbering
> should be the same regardless of the design and/or routing.

Ack. Will move to mt8195.dtsi!

> 
> Ideally this should be described with a proper graph though.
> 
> ChenYu
> 
>>
>> Regards,
>> Angelo
>>
>>>>    1 file changed, 2 insertions(+)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>>>> index 0820e9ba3829..918380697a9a 100644
>>>> --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>>>> +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>>>> @@ -10,6 +10,8 @@
>>>>
>>>>    / {
>>>>           aliases {
>>>> +               dp-intf0 = &dp_intf0;
>>>> +               dp-intf1 = &dp_intf1;
>>>>                   i2c0 = &i2c0;
>>>>                   i2c1 = &i2c1;
>>>>                   i2c2 = &i2c2;
>>>> --
>>>> 2.40.0
>>>>
>>>>
>>>
>>