linux-kernel - Re: [RFC PATCH v10 6/9] media: tegra: Add Tegra210 Video input driver

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Message-ID: <aabaecc4-3494-0137-7d2b-853304bfa68b@gmail.com>
Date:   Sun, 26 Apr 2020 04:26:01 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Sowjanya Komatineni <skomatineni@...dia.com>,
        Hans Verkuil <hverkuil@...all.nl>, thierry.reding@...il.com,
        jonathanh@...dia.com, frankc@...dia.com, sakari.ailus@....fi,
        helen.koike@...labora.com
Cc:     sboyd@...nel.org, linux-media@...r.kernel.org,
        devicetree@...r.kernel.org, linux-clk@...r.kernel.org,
        linux-tegra@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v10 6/9] media: tegra: Add Tegra210 Video input driver

26.04.2020 04:08, Sowjanya Komatineni пишет:
> 
> On 4/25/20 5:41 PM, Sowjanya Komatineni wrote:
>>
>> On 4/25/20 5:36 PM, Dmitry Osipenko wrote:
>>> External email: Use caution opening links or attachments
>>>
>>>
>>> 25.04.2020 12:36, Hans Verkuil пишет:
>>> ...
>>>>> The media/tegra/ sounds a bit too generic, the media/tegra-vi/ path
>>>>> should better reflect the driver, IMO.
>>>>>
>>>>> It also should be better to name the compiled kernel module as
>>>>> tegra-vi,
>>>>> IMO.
>>>>>
>>>> The driver name and the directory should be in sync, so either
>>>> tegra-video
>>>> or tegra-vi for both. I have no preference myself, as long as they
>>>> are the
>>>> same.
>>>>
>>>> This can be done as a follow-up patch.
>>> Given that this driver isn't going to be reused by older pre-Tegra210
>>> SoCs, perhaps it will also be worthwhile to name it as tegra210-vi or
>>> tegra210-video.
>>
>> Can you explain what do you meant by can't be reused for pre-tegra210
>> or for tegra186/194?

It looks to me that at least all those hardcoded HW format IDs do not
match the older SoCs.

>> support for other tegra's can be added to same tegra-video driver.
>> tegra-video host1x driver can be updated to add other tegra's vi and
>> csi compatibles to host1x subdevs and vi and csi driver can be updated
>> to add other tegra soc data and need to add coresponding
>> tegra186/194/xxx.c file with tegra specific prog sequence
>>
> Same tegra-video.ko can be used for all tegra soc as driver supports
> adding other soc related as well.

Well, I'm still not sure why you would want to have all the unnecessary
code of a different SoCs shared within the same kernel module, it will
be quite be a lot wasted space in comparison to a used part of the driver.

The driver will need to have a bit better separation if it's supposed to
have a common core for all SoCs. Each incompatible VI/CSI hardware
version should have its own kernel module.

> Also was thinking instead of renaming media/tegra as media/tegra-vi,
> probably we can rename as media/tegra-video so it will be inline with
> module name we already chosen and also mainly we have vi and csi with in
> that so instead of tegra-vi probably we can use media/tegra-video?

The tegra-video should be okay, although the "video" part sounds a bit
too broad since video could mean a lot of things. I think downstream
kernel uses (or at least used) the tegra-camera name for the driver,
perhaps it could be a reasonable variant as well.