[RFC] Adds support for ConfigFS to VKMS!

[José Expósito]

Hi Louis,

On Fri, Aug 09, 2024 at 07:59:49PM +0200, Louis Chauvet wrote:
> Hi everyone,
> 
> I'm excited to share some good news! I've recently completed the addition 
> of a ConfigFS interface to VKMS, which allows to configure VKMS from 
> user-space, at runtime. You should be able to:
> - Create new devices
> - Create planes/crtc/encoders
> - Configure rotation, color range, color encoding
> - Link planes, crtc and encoders.

Nice! Thanks for the hard work.

During the last 2 or 3 weeks I worked on ConfigFS support as well and
I have an RFC series ready to be sent to the mailing list.
My version is a bit simpler than yours because it doesn't implement extra
features (color formats, etc) and it can be applied on drm-misc-next.
I'll send the RFC as soon as I finish typing this email :)

I don't have any preference about which ConfigFS series we end up
using as long as we get the feature implemented.
Instead, I think that having 2 different implementations is a great
opportunity for better reviews because we have a good idea about how
the implementation might look like and it'll make easier to find bugs.

> The entire series can be found on my GitHub repository:
> https://github.com/Fomys/linux/tree/b4/new-configfs
> 
> This series is big, consisting of over 40 commits. Although it's not 
> completely cleaned up, all commits compile successfully and (almost) pass 
> checkpatch.
> 
> I plan to split this series into several smaller ones:
> 
>  - Adding support for additional color formats
> 	4a4f75873cca..d74006d7f9c4
>  - Reintroducing the writeback algorithm
> 	9e74d259e1be..f839dcf6a7d8
>  - Clarifying documentation
> 	b3bfd0ba2283..93945f0fbfc7
>  - Properly splitting headers
> 	c70018038572..67258bd8a180
>  - Switching to drmm_ helpers
> 	844e701e1d6d..f3050d125f64
>  - Using a proper platform device driver
> 	4658f99dfe3e..a3258e4d7550
>  - Introducing a vkms_config structure
> 	95ad6da46638..5b2d080b4626
>  - Adding ConfigFS support
> 	866ad75102ae..f900ad18ab8c
> 
> What's currently missing:
> 
>  - A deep cleanup to ensure checkpatch compliance and proper
>    functionality for every commit
>  - Updating documentation
>  - Reviews 
> 
> The primary area where I need assistance is reviews and testers. I'm aware 
> that Maìra is very busy and can't review quickly, but any other 
> individuals who can test and/or review this series would be greatly 
> appreciated.
> 
> My next step is to add connector support, but as I will use this work and 
> my previous series [1], I would like to see it merged first.
> 
> If any of the original authors would like to be credited for 
> their contributions, please let me know. I rewrote most of the code, but 
> the general idea was originally from them.
> 
> José, I am sorry, I think I missed your mail where you told me you already 
> reviewed some commits: 
> 
> > I reviewed the first 9 patches and added a few comments on your
> > GitHub fork.
> 
> I am not able to find any comments, can you send me the link to the page 
> with them? I would like to read/apply them before submitting the first 
> part of the series.

My comments were in the GitHub commits, but I think they were lost after
rebasing/force pushing.

Hopefully, I saved a copy of your patches with my suggestions applied and
commit messages where missing:
https://github.com/JoseExposito/linux/commits/patch-vkms-header-refactor/

I think you should be able to extract the diff easily.

It might be a better idea to share the patches in the mailing list for
broader discussion and to avoid loosing review comments.

Thanks a lot for your work Louis!
José Expósito

> Thanks for your time,
> Louis Chauvet
> 
> [1]: https://lore.kernel.org/all/20240809-yuv-v10-0-1a7c764166f7@bootlin.com/
> 
> -- 
> Louis Chauvet, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com