linux-kernel - Re: [PATCH v10 7/7] media: nuvoton: Add driver for NPCM video capture and encode engine

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Date:   Tue, 3 Jan 2023 13:48:23 +0100
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Kun-Fa Lin <milkfafa@...il.com>
Cc:     mchehab@...nel.org, hverkuil-cisco@...all.nl,
        avifishman70@...il.com, tmaimon77@...il.com, tali.perry1@...il.com,
        venture@...gle.com, yuenn@...gle.com, benjaminfair@...gle.com,
        robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        andrzej.p@...labora.com, kwliu@...oton.com,
        devicetree@...r.kernel.org, openbmc@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org, kflin@...oton.com,
        linux-media@...r.kernel.org
Subject: Re: [PATCH v10 7/7] media: nuvoton: Add driver for NPCM video capture
 and encode engine

Dear Kun-Fa,


Am 29.12.22 um 09:55 schrieb Kun-Fa Lin:

>>> Add driver for Video Capture/Differentiation Engine (VCD) and Encoding
>>> Compression Engine (ECE) present on Nuvoton NPCM SoCs. The VCD can
>>> capture and differentiate video data from digital or analog sources,
>>
>> “differentiate video data” sounds uncommon to me. Am I just ignorant or
>> is there a better term?
> 
> How about "The VCD can capture a frame from digital video input and
> compare two frames in memory, then the ECE will compress the frame
> data into HEXTITLE format", is it better?

Yes, I prefer your suggestion.

>> Wich VNC viewer and version?
> 
> I used RealVNC version 6.21.1109 to test.
> Do I have to add this information in the commit message?

I do not think there are rules, but I prefer to have the test 
environment and procedure information in the commit message in case 
there are problems, and you want to reproduce things.

>> Maybe also paste the new dev_ log messages you get from one boot.
> 
> Do you mean dev_info/dev_debug messages of the driver?
> If yes, I get these messages from one boot (only dev_info will be
> printed in default):
> 
> npcm-video f0810000.video: assigned reserved memory node framebuffer@...3000000
> npcm-video f0810000.video: NPCM video driver probed

Yes, that is what I meant. Maybe even the debug messages.

>> It’d be great if you noted the datasheet name and revision.
> 
> I can note the datasheet name and revision in the commit message but
> can't provide the file link because it is not public.
> Is it ok with you?

Yes, that would be ok with me.

>>> +static unsigned int npcm_video_ece_get_ed_size(struct npcm_video *video,
>>> +                                            u32 offset, u8 *addr)
>>> +{
>>> +     struct regmap *ece = video->ece.regmap;
>>> +     u32 size, gap, val;
>>
>> Using a fixed size type for variables not needing is, is actually not an
>> optimization [1]. It’d be great, if you went over the whole change-set
>> to use the non-fixed types, where possible. (You can also check the
>> difference with `scripts/bloat-o-meter`.
> 
> So what I have to do is replace "u8/u16/u32" with "unsigned int" for
> generic local variables as much as possible.
> Is my understanding correct?

Yes, I would say so.

>>> +MODULE_AUTHOR("Joseph Liu<kwliu@...oton.com>");
>>> +MODULE_AUTHOR("Marvin Lin<kflin@...oton.com>");
>>
>> Please add a space before the <.
>>
>>> +MODULE_DESCRIPTION("Driver for Nuvoton NPCM Video Capture/Encode Engine");
>>> +MODULE_LICENSE("GPL");
>>
>> Not GPL v2?
> 
> I'll correct them in the next patch.

Awesome.


Kind regards,

Paul