Re: [PATCH v2 2/2] arm64: dts: Add Mediatek X20 Development Board support

[Matthias Brugger <matthias.bgg@gmail.com>]

On 18/07/18 18:43, Manivannan Sadhasivam wrote:
> Hi Matthias,
> 
> On Wed, Jul 18, 2018 at 05:07:38PM +0200, Matthias Brugger wrote:
>>
>>
>> On 17/07/18 16:04, Manivannan Sadhasivam wrote:
>>> Hi Matthias,
>>>
>>> On Mon, Jul 16, 2018 at 03:24:44PM +0200, Matthias Brugger wrote:
>>>> Hi Manivanna,
>>>>
>>>> On 05/06/18 18:34, Manivannan Sadhasivam wrote:
>>>>> Add initial device tree support for Mediatek X20 Development Board
>>>>> based on MT6797 Deca core SoC. This board is one of the 96Boards
>>>>> Consumer Edition platform.
>>>>>
>>>>> Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
>>>>> ---
>>>>>  arch/arm64/boot/dts/mediatek/Makefile         |  1 +
>>>>>  .../boot/dts/mediatek/mt6797-x20-dev.dts      | 33 +++++++++++++++++++
>>>>>  2 files changed, 34 insertions(+)
>>>>>  create mode 100644 arch/arm64/boot/dts/mediatek/mt6797-x20-dev.dts
>>>>>
>>>>> diff --git a/arch/arm64/boot/dts/mediatek/Makefile b/arch/arm64/boot/dts/mediatek/Makefile
>>>>> index ac17f60f998c..5b7fd6ad96e4 100644
>>>>> --- a/arch/arm64/boot/dts/mediatek/Makefile
>>>>> +++ b/arch/arm64/boot/dts/mediatek/Makefile
>>>>> @@ -3,5 +3,6 @@ dtb-$(CONFIG_ARCH_MEDIATEK) += mt2712-evb.dtb
>>>>>  dtb-$(CONFIG_ARCH_MEDIATEK) += mt6755-evb.dtb
>>>>>  dtb-$(CONFIG_ARCH_MEDIATEK) += mt6795-evb.dtb
>>>>>  dtb-$(CONFIG_ARCH_MEDIATEK) += mt6797-evb.dtb
>>>>> +dtb-$(CONFIG_ARCH_MEDIATEK) += mt6797-x20-dev.dtb
>>>>>  dtb-$(CONFIG_ARCH_MEDIATEK) += mt7622-rfb1.dtb
>>>>>  dtb-$(CONFIG_ARCH_MEDIATEK) += mt8173-evb.dtb
>>>>> diff --git a/arch/arm64/boot/dts/mediatek/mt6797-x20-dev.dts b/arch/arm64/boot/dts/mediatek/mt6797-x20-dev.dts
>>>>> new file mode 100644
>>>>> index 000000000000..2c09ca95d9e2
>>>>> --- /dev/null
>>>>> +++ b/arch/arm64/boot/dts/mediatek/mt6797-x20-dev.dts
>>>>> @@ -0,0 +1,33 @@
>>>>> +// SPDX-License-Identifier: GPL-2.0
>>>>> +/*
>>>>> + * Device Tree Source for MediaTek X20 Development Board
>>>>> + *
>>>>> + * Copyright (C) 2018, Linaro Ltd.
>>>>> + *
>>>>> + */
>>>>> +
>>>>> +/dts-v1/;
>>>>> +
>>>>> +#include "mt6797.dtsi"
>>>>> +
>>>>> +/ {
>>>>> +	model = "Mediatek X20 Development Board";
>>>>> +	compatible = "archermind,mt6797-x20-dev", "mediatek,mt6797";
>>>>> +
>>>>> +	aliases {
>>>>> +		serial0 = &uart1;
>>>>> +	};
>>>>
>>>> Sorry for the late answer.
>>>> Why did you use uart1 instead of uart0?
>>>> I know that uart0 is used by the bootloader, but because of their exotic flash
>>>> procedure I find it quite useful to see this messages in my serial connection.
>>>> Of course you can only use 921600 baudrate then.
>>>>
>>>
>>> The reason is, most of the Mezzanine boards use USB to UART bridge on the
>>> UART1 port available on the Low Speed Expansion header. Additionally, the
>>> convention followed by most of the Consumer Edition 96Boards is to use UART1
>>> as the debug serial port. That's why eventhough the bootloader is using UART0,
>>> I forced the kernel to use UART1.
>>>
>>
>> Sounds reasonable, I don't have this 96 boards adapter and I forgot about it.
>>
> 
> That's fine :)
> 
>>>>> +
>>>>> +	memory@40000000 {
>>>>> +		device_type = "memory";
>>>>> +		reg = <0 0x40000000 0 0x1e605000>;
>>>>
>>>> How comes this strange number for the memory size?
>>>>
>>>
>>> Actually, the memory size is extracted from the downstream kernel [1].
>>>
>>
>> Hm, Archermind "Helio X20 Development Board Hardware Manual" talks about 2GB
>> LPDDR3-SDRAM. Would you mind to check if that is actually true?
>>
> 
> Yes, it is 2GB. Shall I change the size to 0x80000000?
> 

Best would be if you boot the machine with this value and see if things look
sane. Then resubmit. The other option is to resubmit and I'll check it tomorrow :)

Let me know if you can't do it for tomorrow morning. I plan to submit the pull
requests tomorrow as I'm through nearly all open patches (yes, two days earlier
\o/ )

Best regards,
Matthias

> Thanks,
> Mani
> 
>>>> BTW do you know the differences between the EVB board and the x20 one?
>>>> I used the evb dts for booting up to now.
>>>>
>>>
>>> Sorry, I don't know the difference between both boards!
>>
>> Sure, no problem :)
>>
>> Regards,
>> Matthias
>>
>>>
>>> Thanks,
>>> Mani
>>>
>>> [1] https://github.com/helio-x20/linux/blob/helio-x20/arch/arm64/boot/dts/amt6797_64_open.dts#L8
>>>
>>>> Best regards,
>>>> Matthias
>>>>
>>>>> +	};
>>>>> +
>>>>> +	chosen {
>>>>> +		stdout-path = "serial0:115200n8";
>>>>> +	};
>>>>> +};
>>>>> +
>>>>> +&uart1 {
>>>>> +	status = "okay";
>>>>> +};
>>>>>