linux-kernel - Re: [PATCH v3 4/4] arm64: dts: mediatek: add mt6765 support

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Message-ID: <304dc0a7-bcba-961c-40f4-b324ecc2d003@arm.com>
Date:   Wed, 4 Jul 2018 08:59:56 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Mars Cheng <mars.cheng@...iatek.com>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        CC Hwang <cc.hwang@...iatek.com>,
        Loda Chou <loda.chou@...iatek.com>,
        linux-kernel@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        devicetree@...r.kernel.org, wsd_upstream@...iatek.com,
        linux-serial@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 4/4] arm64: dts: mediatek: add mt6765 support

On 04/07/18 08:47, Mars Cheng wrote:
> Hi Marc
> 
> On Wed, 2018-07-04 at 08:35 +0100, Marc Zyngier wrote:
>> On 04/07/18 02:52, Mars Cheng wrote:
>>> This adds basic chip support for MT6765 SoC.
>>>
>>> Signed-off-by: Mars Cheng <mars.cheng@...iatek.com>
>>> ---
>>>  arch/arm64/boot/dts/mediatek/Makefile       |    1 +
>>>  arch/arm64/boot/dts/mediatek/mt6765-evb.dts |   33 ++++++
>>>  arch/arm64/boot/dts/mediatek/mt6765.dtsi    |  155 +++++++++++++++++++++++++++
>>>  3 files changed, 189 insertions(+)
>>>  create mode 100644 arch/arm64/boot/dts/mediatek/mt6765-evb.dts
>>>  create mode 100644 arch/arm64/boot/dts/mediatek/mt6765.dtsi
>>>
>>
>> [...]
>>
>>> +
>>> +		gic: interrupt-controller@...0000 {
>>> +			compatible = "arm,gic-v3";
>>> +			#interrupt-cells = <3>;
>>> +			#address-cells = <2>;
>>> +			#size-cells = <2>;
>>> +			#redistributor-regions = <1>;
>>> +			interrupt-parent = <&gic>;
>>> +			interrupt-controller;
>>> +			reg = <0 0x0c000000 0 0x40000>, // distributor
>>> +			      <0 0x0c100000 0 0x200000>, // redistributor
>>> +			      <0 0x0c400000 0 0x40000>; // gicc
>>
>> For the second time: please add *all* the GIC CPU interface regions,
>> described in the Cortex-A53 TRM[1] (GICC, GICH, and GICV).
>>
> 
> MT6765 has no GICH/GICV/ITS in mediatek design. Have confirmed with our
> designer.  

The only way *not* to have GICH or GICV is to assert GICCDISABLE on the
CPU, in which case you don't have GICC either, nor any support for the
GICv3 at all. So either the designer is wrong or the documentation is
wrong. Which one is it, do you think?

As for the ITS, that's a perfectly optional part of the design, and not
part of the CPU.

> MT6797 had similar question from you. Sorry for not mentioned it first.
> 
> http://lists.infradead.org/pipermail/linux-mediatek/2017-February/008074.html

Well, that's wrong too.

	M.
-- 
Jazz is not dead. It just smells funny...