linux-kernel - Re: [PATCH v14 1/2] drm: add kms driver for loongson display controller

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Message-ID: <0e5e4a4b-1426-ffae-e958-cf8f9aece166@xen0n.name>
Date:   Mon, 22 May 2023 18:25:12 +0800
From:   WANG Xuerui <kernel@...0n.name>
To:     Sui Jingfeng <15330273260@....cn>,
        Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
        Maxime Ripard <mripard@...nel.org>,
        Thomas Zimmermann <tzimmermann@...e.de>,
        David Airlie <airlied@...il.com>,
        Daniel Vetter <daniel@...ll.ch>, Li Yi <liyi@...ngson.cn>,
        Sumit Semwal <sumit.semwal@...aro.org>,
        Christian Koenig <christian.koenig@....com>,
        Emil Velikov <emil.l.velikov@...il.com>
Cc:     linaro-mm-sig@...ts.linaro.org, loongson-kernel@...ts.loongnix.cn,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        Javier Martinez Canillas <javierm@...hat.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Liu Peibao <liupeibao@...ngson.cn>, linux-media@...r.kernel.org
Subject: Re: [PATCH v14 1/2] drm: add kms driver for loongson display
 controller

On 2023/5/22 18:17, Sui Jingfeng wrote:
> Hi,
> 
> On 2023/5/22 18:05, WANG Xuerui wrote:
>> On 2023/5/22 17:49, Sui Jingfeng wrote:
>>> Hi,
>>>
>>> On 2023/5/22 17:28, WANG Xuerui wrote:
>>>> On 2023/5/22 17:25, Sui Jingfeng wrote:
>>>>> Hi,
>>>>>
>>>>> On 2023/5/21 20:21, WANG Xuerui wrote:
>>>>>>> + * LS3A4000/LS3A5000/LS3A6000 CPU, they are equipped with 
>>>>>>> on-board video RAM
>>>>>>> + * typically. While LS2K0500/LS2K1000/LS2K2000 are low cost SoCs 
>>>>>>> which share
>>>>>>> + * the system RAM as video RAM, they don't has a dediacated VRAM.
>>>>>>
>>>>>> CPU models are not typically prefixed with "LS", so "Loongson 
>>>>>> 3A4000/3A5000/3A6000".
>>>>>>
>>>>> Here is because when you do programming, variable name should 
>>>>> prefix with letters.
>>>>
>>>> Commit messages, comments, and log messages etc. are natural 
>>>> language, so it's better to treat them differently. No problem to 
>>>> keep code as-is IMO.
>>>>
>>> Then you get two name for a single chip,  take  LS7A1000 as an example.
>>>
>>> You name it as Loongson 7A1000 in commit message,  and then you have 
>>> to define another name in the code,  say LS7A1000.
>>>
>>> "Loongson 7A1000" is too long,  not as compact as LS7A1000.
>>>
>>> This also avoid bind the company name to a specific product, because 
>>> a company can produce many product.
>>
>> Nah, the existing convention is "LS7Xxxxx" for bridges and "Loongson 
>> 3Axxxx" for CPUs (SoCs like 2K fall under this category too). It's 
>> better to stick with existing practice so it would be familiar to 
>> long-time Loongson/LoongArch developers, but I personally don't think 
>> it will hamper understanding if you feel like doing otherwise.
>>
> Can you explain why it is better?
> 
> is it that the already existing is better ?

It's not about subjective perception of "better" or "worse", but about 
tree-wide consistency, and about reducing any potential confusion from 
newcomers. I remember Huacai once pointing out that outsiders usually 
have a hard time remembering "1, 2, and 3 are CPUs, some 2 are SoCs, 7 
are bridge chips", and consistently referring to the bridge chips 
throughout the tree as "LS7A" helped.

In any case, for the sake of consistency, you can definitely refer to 
the CPU models in natural language like "LS3Axxxx"; just make sure to 
refactor for example every occurrence in arch/loongarch and other parts 
of drivers/. That's a lot of churn, though, so I don't expect such 
changes to get accepted, and that's why the tree-wide consistency should 
be favored over the local one.

-- 
WANG "xen0n" Xuerui

Linux/LoongArch mailing list: https://lore.kernel.org/loongarch/