Message-ID: <aKgxcWYq-WZAFwsx@valkosipuli.retiisi.eu>
Date: Fri, 22 Aug 2025 08:59:29 +0000
From: Sakari Ailus <sakari.ailus@....fi>
To: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	Hans Verkuil <hverkuil@...all.nl>,
	Ricardo Ribalda <ribalda@...omium.org>
Subject: Re: [PATCH v4 3/5] docs: media: update maintainer-entry-profile for
 multi-committers

Hi Mauro,

On Fri, Aug 22, 2025 at 10:23:46AM +0200, Mauro Carvalho Chehab wrote:
> Em Thu, 21 Aug 2025 12:26:18 +0000
> Sakari Ailus <sakari.ailus@....fi> escreveu:
> 
> > Hi Mauro,
> > 
> > This seems pretty good, there are some comments mostly on technicalities
> > below.
> > 
> > On Tue, Dec 03, 2024 at 10:35:47AM +0100, Mauro Carvalho Chehab wrote:
> > > As the media subsystem will experiment with a multi-committers model,
> > > update the Maintainer's entry profile to the new rules.
> > > 
> > > Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
> > > Signed-off-by: Hans Verkuil <hverkuil@...all.nl>
> > > Reviewed-by: Ricardo Ribalda <ribalda@...omium.org>
> > > ---
> > >  .../media/maintainer-entry-profile.rst        | 241 ++++++++++++++----
> > >  1 file changed, 189 insertions(+), 52 deletions(-)
> > > 
> > > diff --git a/Documentation/driver-api/media/maintainer-entry-profile.rst b/Documentation/driver-api/media/maintainer-entry-profile.rst
> > > index ffc712a5f632..101f6df6374f 100644
> > > --- a/Documentation/driver-api/media/maintainer-entry-profile.rst
> > > +++ b/Documentation/driver-api/media/maintainer-entry-profile.rst
> > > @@ -4,11 +4,12 @@ Media Subsystem Profile
> > >  Overview
> > >  --------
> > >  
> > > -The media subsystem covers support for a variety of devices: stream
> > > -capture, analog and digital TV streams, cameras, remote controllers, HDMI CEC
> > > -and media pipeline control.
> > > +The Linux Media Community (aka: the LinuxTV Community) covers support for a
> > > +variety of devices: stream capture, analog and digital TV streams, cameras,
> > > +remote controllers, HDMI CEC and media pipeline control.  
> > 
> > I'd make a difference here between the Media tree and the Linux Media
> > community. The drivers in the Media tree support these devices whereas the
> > community generally works on this codebase.
> > 
> > >  
> > > -It covers, mainly, the contents of those directories:
> > > +They consist of developers who work with the Linux Kernel media subsystem,
> > > +which covers, mainly, the contents of those directories:  
> > 
> > If you want to refer to the community here, I'd use that word.
> 
> What about this:
> 
> <text>
> The Linux Media Community (aka: the LinuxTV Community) consist of developers 
> who work with the Linux Kernel media subsystem, together with users who
> benefit from such develoment and help testing the developed code.

How about, with slight modifications:

The Linux Media Community (aka: the LinuxTV Community) is formed of
developers working on Linux Kernel Media Subsystem, together with users.

> 
> They work on the top of the Media tree, which has code to support a    
> variety of devices: stream capture, analog and digital TV streams, cameras,
> remote controllers, HDMI CEC and media pipeline control.
> 
> The Media tree is mainly responsible to be the main source of the
> code under development with the contents of those directories:
> 
>   - drivers/media
>   - drivers/staging/media
>   - Documentation/admin-guide/media
>   - Documentation/driver-api/media
>   - Documentation/userspace-api/media
>   - Documentation/devicetree/bindings/media/\ [1]_
>   - include/media
> </text>
> 
> > 
> > >  
> > >    - drivers/media
> > >    - drivers/staging/media
> > > @@ -27,19 +28,158 @@ It covers, mainly, the contents of those directories:
> > >  Both media userspace and Kernel APIs are documented and the documentation
> > >  must be kept in sync with the API changes. It means that all patches that
> > >  add new features to the subsystem must also bring changes to the
> > > -corresponding API files.
> > > +corresponding API documentation files.  
> > 
> > I'd drop " files" as the documentation is split between C source code files
> > and ReST nowadays.
> 
> OK.
> 
> > > -Due to the size and wide scope of the media subsystem, media's
> > > -maintainership model is to have sub-maintainers that have a broad
> > > -knowledge of a specific aspect of the subsystem. It is the sub-maintainers'
> > > -task to review the patches, providing feedback to users if the patches are
> > > +Due to the size and wide scope of the media subsystem, the media's
> > > +maintainership model is to have committers that have a broad knowledge of  
> > 
> > Maintainership or maintenance?
> > 
> > s/is to have/recognises/ ?
> 
> OK.
>  
> > > +a specific aspect of the subsystem. It is the committers' task to
> > > +review the patches, providing feedback to users if the patches are
> > >  following the subsystem rules and are properly using the media kernel and
> > >  userspace APIs.
> > >  
> > > -Patches for the media subsystem must be sent to the media mailing list
> > > -at linux-media@...r.kernel.org as plain text only e-mail. Emails with
> > > -HTML will be automatically rejected by the mail server. It could be wise
> > > -to also copy the sub-maintainer(s).
> > > +Media committers
> > > +----------------
> > > +
> > > +In the media subsystem, there are experienced developers who can push
> > > +patches directly to the development tree. These developers are called
> > > +Media committers and are divided into the following categories:
> > > +
> > > +- Committers:
> > > +    contributors for one or more drivers within the media subsystem.
> > > +    They can push changes to the tree that do not affect the core or ABI.  
> > 
> > Question to Ricardo -- sorry if I already have asked this: can this be
> > enforced?
> > 
> > > +
> > > +- Core committers:
> > > +    responsible for part of the media core. They are typically
> > > +    responsible for one or more drivers within the media subsystem, but, besides
> > > +    that, they can also merge patches that change the code common to multiple
> > > +    drivers, including the kernel internal API.  
> > 
> > This doesn't say clearly whether e.g. the V4L2 or MC frameworks are
> > included or not. I think they should be and this should be mentioned. Same
> > for videobuf2.
> 
> The problem of specifying what the core via frameworks, vb2, etc is that
> this would require constant maintainance. Core is everything that is not
> inside a driver for an specific driver.
> 
> We called this here as "the code common to multiple drivers". For me it
> is clear, but if you have a better generic term, I'm all ears.

How about:

- Core committers:
    responsible for part of the Media Core, including V4L2, Media
    controller, Videobuf2, CEC and DVB frameworks. They are typically
    responsible for one or more drivers within the Media Subsystem, but,
    besides that, they can also merge patches that change the code common
    to multiple drivers, including the kernel internal API.

I think we should define Media Subsystem, Media Core and possibly Media
Community in the glossary but I'd do that after merging this set.

> 
> > 
> > > +
> > > +- Subsystem maintainers:
> > > +    responsible for the subsystem as a whole, with access to the
> > > +    entire subsystem.
> > > +
> > > +    API/ABI changes are done via consensus between subsystem maintainers\ [2]_.
> > > +
> > > +    Only subsystem maintainers push changes that affect the userspace
> > > +    API/ABI. Committers may push ABI/API changes on their commits if they
> > > +    have approvals from subsystem maintainers.
> > > +
> > > +All media committers shall explicitly agree with the Kernel development process
> > > +as described at Documentation/process/index.rst and to the Kernel
> > > +development rules inside the Kernel documentation, including its code of
> > > +conduct.  
> > 
> > Is there a need to mention this? Aren't people generally expected to
> > follow the process anyway?
> 
> There's a big difference between "generally expected" and "have to agree".
> The goal here is really to prevent having bad committers as we had in the
> past on our previous multicommiters model before we moved to git. If this
> ever have again, by having an explicit agreement, one cannot deny he/she
> didn't know the rules.

Fair enough. Either way, enforment is discretionary so I think this is
fine -- mistakes tend to happen, to everybody, at least in some extent.

> 
> > > +
> > > +.. [2] Everything that would break backward compatibility with existing
> > > +       non-kernel code are API/ABI changes. This includes ioctl and sysfs
> > > +       interfaces, v4l2 controls, and their behaviors.
> > > +
> > > +Media development tree
> > > +----------------------
> > > +
> > > +The main development tree used by the media subsystem is hosted at LinuxTV.org,
> > > +where we also maintain news about the subsystem, wiki pages and a patchwork
> > > +instance where we track patches though their lifetime.
> > > +
> > > +The main tree used by media developers is at:
> > > +
> > > +https://git.linuxtv.org/media.git/
> > > +
> > > +.. _Media development workflow:
> > > +
> > > +Media development workflow
> > > +++++++++++++++++++++++++++
> > > +
> > > +All changes for the media subsystem must be sent first as e-mails to the  
> > 
> > s/must/shall/ ?
> 
> OK.
> 
> > > +media mailing list, following the process documented at
> > > +Documentation/process/index.rst.
> > > +
> > > +It means that patches shall be submitted as plain text only via e-mail to
> > > +linux-media@...r.kernel.org (aka: LMML). While subscription is not mandatory,
> > > +you can find details about how to subscribe to it and to see its archives at:
> > > +
> > > +  https://subspace.kernel.org/vger.kernel.org.html
> > > +
> > > +Emails with HTML will be automatically rejected by the mail server.
> > > +
> > > +It could be wise to also copy the media committer(s). You should use
> > > +``scripts/get_maintainers.pl`` to identify whom else needs to be copied.
> > > +Please always copy driver's authors and maintainers.
> > > +
> > > +To minimize the chance of merge conflicts for your patch series, and make
> > > +easier to backport patches to stable Kernels, we recommend that you use the
> > > +following baseline for your patch series:
> > > +
> > > +1. Features for the next mainline release:
> > > +
> > > +   - baseline shall be media.git ``next`` branch;
> > > +
> > > +2. Bug fixes for the current mainline release:
> > > +
> > > +   - baseline shall be the latest mainline release or media.git ``fixes``
> > > +     if changes depend on a fix already merged;
> > > +
> > > +3. Bug fixes for the next mainline release:
> > > +
> > > +   - baseline shall be a prepatch release (-rcX) or media.git ``fixes``
> > > +     if changes depend on a fix already merged. It is also
> > > +     fine to use media.git ``next`` as baseline for such patches if such
> > > +     patches apply cleanly on ``fixes``.
> > > +
> > > +.. Note::
> > > +
> > > +   See https://www.kernel.org/category/releases.html for an overview
> > > +   about Kernel release types.
> > > +
> > > +Patches with fixes shall have:
> > > +
> > > +- a ``Fixes:`` tag pointing to the first commit that introduced the bug;
> > > +- when applicable, a ``Cc: stable@...r.kernel.org``.
> > > +
> > > +Patches that were fixing bugs publicly reported by someone at the
> > > +linux-media@...r.kernel.org mailing list shall have:
> > > +
> > > +- a ``Reported-by:`` tag immediately followed by a ``Closes:`` tag.
> > > +
> > > +Patches that change API shall update documentation accordingly at the
> > > +same patch series.
> > > +
> > > +See Documentation/process/index.rst for more details about e-mail submission.
> > > +
> > > +Once a patch is submitted, it may follow either one of the following
> > > +workflows:
> > > +
> > > +a. Pull request workflow: patches are handled by subsystem maintainers::
> > > +
> > > +     +-------+   +---------+   +-------+   +-----------------------+   +---------+
> > > +     |e-mail |-->|patchwork|-->|pull   |-->|maintainers merge      |-->|media.git|
> > > +     |to LMML|   |picks it |   |request|   |in media-committers.git|   +---------+
> > > +     +-------+   +---------+   +-------+   +-----------------------+
> > > +
> > > +   For this workflow, pull requests can be generated by committers,
> > > +   former committers, subsystem maintainers or by trusted long-time
> > > +   contributors. If you are not in such group, please don't submit
> > > +   pull requests, as they will not be processed.
> > > +
> > > +b. Committers' workflow: patches are handled by media committers::
> > > +
> > > +     +-------+   +---------+   +--------------------+   +-----------+   +---------+
> > > +     |e-mail |-->|patchwork|-->|committers merge at |-->|maintainers|-->|media.git|
> > > +     |to LMML|   |picks it |   |media-committers.git|   |approval   |   +---------+
> > > +     +-------+   +---------+   +--------------------+   +-----------+
> > > +
> > > +On both workflows, all patches shall be properly reviewed at
> > > +linux-media@...r.kernel.org (LMML) before being merged at media-committers.git.
> > > +
> > > +When patches are picked by patchwork and when merged at media-committers,
> > > +CI bots will check for errors and may provide e-mail feedback about
> > > +patch problems. When this happens, the patch submitter must fix them, or  
> > 
> > I'd remove the latter comma.
> 
> OK.
> 
> > 
> > > +explain why the errors are false positives.
> > > +
> > > +Patches will only be moved to the next stage in those two workflows if they
> > > +pass on CI or if there are false-positives in the CI reports.
> > > +
> > > +Failures during e-mail submission
> > > ++++++++++++++++++++++++++++++++++
> > >  
> > >  Media's workflow is heavily based on Patchwork, meaning that, once a patch
> > >  is submitted, the e-mail will first be accepted by the mailing list
> > > @@ -47,51 +187,49 @@ server, and, after a while, it should appear at:
> > >  
> > >     - https://patchwork.linuxtv.org/project/linux-media/list/
> > >  
> > > -If it doesn't automatically appear there after a few minutes, then
> > > +If it doesn't automatically appear there after some time [3]_, then
> > >  probably something went wrong on your submission. Please check if the
> > > -email is in plain text\ [2]_ only and if your emailer is not mangling
> > > +email is in plain text\ [4]_ only and if your emailer is not mangling
> > >  whitespaces before complaining or submitting them again.
> > >  
> > > -You can check if the mailing list server accepted your patch, by looking at:
> > > +To troubleshoot problems, you should first check if the mailing list
> > > +server has accepted your patch, by looking at:
> > >  
> > >     - https://lore.kernel.org/linux-media/
> > >  
> > > -.. [2] If your email contains HTML, the mailing list server will simply
> > > +If the patch is there and not at patchwork, it is likely that your e-mailer
> > > +mangled the patch. Patchwork internally has logic that checks if the
> > > +received e-mail contains a valid patch. Any whitespace and new line
> > > +breakages mangling the patch won't be recognized by patchwork, thus such
> > > +patch will be rejected.
> > > +
> > > +.. [3] It usually takes a few minutes for the patch to arrive, but
> > > +       the e-mail server may be busy, so it may take up to a few hours
> > > +       for a patch to be picked by patchwork.  
> > 
> > I'd just refer to "longer" in the latter case; there are no fixed time
> > limits anyway.
> > 
> 
> OK.
> 
> > > +
> > > +.. [4] If your email contains HTML, the mailing list server will simply
> > >         drop it, without any further notice.
> > >  
> > > +.. _media-developers-gpg:
> > >  
> > > -Media maintainers
> > > -+++++++++++++++++
> > > +Authentication for pull and merge requests
> > > +++++++++++++++++++++++++++++++++++++++++++
> > >  
> > > -At the media subsystem, we have a group of senior developers that
> > > -are responsible for doing the code reviews at the drivers (also known as
> > > -sub-maintainers), and another senior developer responsible for the
> > > -subsystem as a whole. For core changes, whenever possible, multiple
> > > -media maintainers do the review.
> > > +The authenticity of developers submitting pull requests and merge requests
> > > +shall be validated by using PGP signing at some moment.
> > > +See: :ref:`kernel_org_trust_repository`.
> > >  
> > > -The media maintainers that work on specific areas of the subsystem are:
> > > +With the pull request workflow, pull requests shall use PGP-signed tags.
> > >  
> > > -- Remote Controllers (infrared):
> > > -    Sean Young <sean@...s.org>
> > > +For more details about PGP sign, please read
> > > +Documentation/process/maintainer-pgp-guide.rst.
> > >  
> > > -- HDMI CEC:
> > > -    Hans Verkuil <hverkuil@...all.nl>
> > > +Subsystem maintainers
> > > +---------------------
> > >  
> > > -- Media controller drivers:
> > > -    Laurent Pinchart <laurent.pinchart@...asonboard.com>
> > > -
> > > -- ISP, v4l2-async, v4l2-fwnode, v4l2-flash-led-class and Sensor drivers:
> > > -    Sakari Ailus <sakari.ailus@...ux.intel.com>
> > > -
> > > -- V4L2 drivers and core V4L2 frameworks:
> > > -    Hans Verkuil <hverkuil@...all.nl>
> > > -
> > > -The subsystem maintainer is:
> > > -  Mauro Carvalho Chehab <mchehab@...nel.org>
> > > -
> > > -Media maintainers may delegate a patch to other media maintainers as needed.
> > > -On such case, checkpatch's ``delegate`` field indicates who's currently
> > > -responsible for reviewing a patch.
> > > +The subsystem maintainers are:
> > > +  - Mauro Carvalho Chehab <mchehab@...nel.org> and
> > > +  - Hans Verkuil <hverkuil@...all.nl>
> > >  
> > >  Submit Checklist Addendum
> > >  -------------------------
> > > @@ -106,18 +244,15 @@ that should be used in order to check if the drivers are properly
> > >  implementing the media APIs:
> > >  
> > >  ====================	=======================================================
> > > -Type			Tool
> > > +Type			Utility
> > >  ====================	=======================================================
> > > -V4L2 drivers\ [3]_	``v4l2-compliance``
> > > +V4L2 drivers\ [5]_	``v4l2-compliance``
> > >  V4L2 virtual drivers	``contrib/test/test-media``
> > >  CEC drivers		``cec-compliance``
> > >  ====================	=======================================================
> > >  
> > > -.. [3] The ``v4l2-compliance`` also covers the media controller usage inside
> > > -       V4L2 drivers.
> > > -
> > > -Other compilance tools are under development to check other parts of the
> > > -subsystem.
> > > +.. [5] The ``v4l2-compliance`` utility also covers the media controller usage
> > > +       inside V4L2 drivers.
> > >  
> > >  Those tests need to pass before the patches go upstream.
> > >  
> > > @@ -134,6 +269,8 @@ Where the check script is::
> > >  Be sure to not introduce new warnings on your patches without a
> > >  very good reason.
> > >  
> > > +Please see `Media development workflow`_ for e-mail submission rules.
> > > +
> > >  Style Cleanup Patches
> > >  +++++++++++++++++++++
> > >  
> > > @@ -199,7 +336,7 @@ tree between -rc6 and the next -rc1.
> > >  Please notice that the media subsystem is a high traffic one, so it
> > >  could take a while for us to be able to review your patches. Feel free
> > >  to ping if you don't get a feedback in a couple of weeks or to ask
> > > -other developers to publicly add Reviewed-by and, more importantly,
> > > +other developers to publicly add ``Reviewed-by:`` and, more importantly,
> > >  ``Tested-by:`` tags.
> > >  
> > >  Please note that we expect a detailed description for ``Tested-by:``,  
> > 

-- 
Regards,

Sakari Ailus

Powered by blists - more mailing lists