Re: [PATCH v3 1/3] docs: media: update maintainer-entry-profile for multi-committers

[Sakari Ailus]

Hi Mauro,

On Mon, Dec 02, 2024 at 02:23:34PM +0100, Mauro Carvalho Chehab wrote:
> Em Mon, 2 Dec 2024 12:40:44 +0000
> Sakari Ailus <sakari.ailus@xxxxxx> escreveu:
> 
> > Hi Mauro,
> > 
> > Thanks for the set.
> > 
> > Looks good overall, please still see my comments below.
> > 
> > On Mon, Dec 02, 2024 at 10:26:19AM +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@xxxxxxxxxx>
> > > Signed-off-by: Hans Verkuil <hverkuil@xxxxxxxx>
> > > Reviewed-by: Ricardo Ribalda <ribalda@xxxxxxxxxxxx>
> > > ---
> > >  .../media/maintainer-entry-profile.rst        | 208 ++++++++++++++----
> > >  MAINTAINERS                                   |   1 +
> > >  2 files changed, 163 insertions(+), 46 deletions(-)
> > > 
> > > diff --git a/Documentation/driver-api/media/maintainer-entry-profile.rst b/Documentation/driver-api/media/maintainer-entry-profile.rst
> > > index ffc712a5f632..dc764163cf1c 100644
> > > --- a/Documentation/driver-api/media/maintainer-entry-profile.rst
> > > +++ b/Documentation/driver-api/media/maintainer-entry-profile.rst
> > > @@ -27,19 +27,139 @@ 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.
> > >  
> > > -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
> > > +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@xxxxxxxxxxxxxxx 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  
> > 
> > The media subsystem is generally understood to comprise of what's under
> > drivers/media, this should be referring to the community instead.
> 
> Do you have a proposal for a different text here?

How about:

In the Linux Media community developers with formal status are classified as
follows.

> 
> > 
> > > +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.
> > > +
> > > +- 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.
> > > +
> > > +- Subsystem maintainers:  
> > 
> > s/Subsystem/Media tree/
> 
> Here, we're talking specifically about my hole and Hans, which will
> co-maintain the subsystem with me.. I guess subsystem maintainer is the 
> best to describe it.
> 
> Besides that, we used "media maintainers" in the past with a different
> meaning. Better to not re-use it here.

Seems good, although...

> > 
> > ?
> > > +    responsible for the subsystem as a whole, with access to the

I'd do here:

s/subsystem/Media tree/ or
s/subsystem/Media subsystem/

> > > +    entire subsystem.
> > > +
> > > +    Only subsystem maintainers can push changes that affect the userspace
> > > +    API/ABI.  
> > 
> > This is ambiguous. I think it should intend to say API/ABI changes require
> > approval from Media tree maintainers.
> 
> At the first moment, the idea is to commit them via PRs. So, no such
> commits will be merged by committers/core committers, but yeah, it
> could also be merged directly by a committer if it has our approval.
> 
> In any case, such changes need a consensus from the subsystem maintainers,
> which can just be based on a trust relationship between them with
> regards to certain parts of the subsystem, or via explicit acks.
> 
> Maybe:
> 
> 	API/ABI changes are done via consensus between subsystem
> 	maintainers.
> 
> 	Only subsystem maintainers push changes that affect the userspace
> 	API/ABI. Committers may push directly if they have approvals
> 	from subsystem maintainers.

Seems good to me. These could be in the same paragraph.

> 
> > What constitutes a UAPI change is a topic of discussion on its own. 
> 
> Everything that would break backward compatibility with existing non-kernel
> code are API/ABI changes.
> 
> > Does it
> > require adding a new IOCTL? Taking into use a reserved field? Changing
> > little-used driver behaviour slightly? 
> 
> For all of those, yes: any changes affecting the behavior or fields/nodes
> exported via ioctls and sysfs, including new V4L2 controls are API/ABI changes.
> 
> Some changes at OF are also API/ABI changes, but those can flow via
> committers, provided that OF maintainers added their review or acked-by.
> 
> > Fixing a bug in a driver?
> 
> No, fixing a bug, even if related to ABI/API non-compliance aren't.
> 
> Yet, ABI/API behavior changes at drivers shall not cause regressions.
> 
> I don't think we need to let it clear at the text

Works for me.

> 
> > The first two obviously yes, but the latter two probably not.
> > 
> > Also:
> > 
> > s/Only subsystem maintainers can push/Media tree maintainers' ack is
> > required for/
> > 
> > ?
> > 
> > > +
> > > +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.
> > > +
> > > +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
> > > +media mailing list, following the process documented at  
> > 
> > s/^/linux-/
> > 
> > Also I'd refer to it as "LMML".
> 
> We can add an alias there, but better to be explicit about what mailing
> list we're referring to.

The list is known as the Linux Media mailing list. We should refer it by
that name or an abbreviation (LMML).

> 
> > 
> > > +Documentation/process/index.rst.
> > > +
> > > +It means that patches shall be submitted as plain text only via e-mail to
> > > +linux-media@xxxxxxxxxxxxxxx. 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.
> > > +
> > > +Such patches need to be based against a public branch or tag as follows:
> > > +
> > > +1. Patches for new features need to be based at the ``next`` branch of
> > > +   media.git tree;
> > > +
> > > +2. Fixes against an already released kernel should preferably be against
> > > +   the latest released Kernel. If they require a previously-applied
> > > +   change at media.git tree, they need to be against its ``fixes`` branch.  
> > 
> > This would be a change to the current process that I don't think has been
> > discussed. If I understand correctly, generally this applies to patches
> > that have been merged to the development branch (formerly media stage tree
> > master) with Cc: stable and Fixes: tags.
> 
> 
> Not really a change: this is what we do in practice (except that we renamed
> master to next).

I mean fixes in particular. Fixes are generally meant for an *upcoming*
release, not a past release, and primarily fixing issues that have been
introduced in that cycle. Other bugfixes should go through the normal
process.

How about adding:

Patches with security implications should be handled using a different
process defined in Documentation/process/security-bugs.rst.

> 
> We did discuss that during the LPC week. There was a request there about
> simplifying the trees during media summit with some suggestions. I did a 
> followup meeting with Hans afterwards for us to check what would work best.
> 
> The change is, basically:
> 	media-tree master -> media.git next
> 	media-tree fixes   -> media.git fixes
> 
> 	media-stage master -> media-committers next
> 
> Subsystem maintainers are also merging patches at media-committers fixes,
> in order to let media-ci to test the fixes branch.
> 
> As agreed during the media summit, only subsystem maintainers will be
> merging fixes patches.
> 
> > > +
> > > +3. Fixes for issues not present at the latest released kernel shall
> > > +   be either against a -rc kernel for an upcoming release or
> > > +   against the ``fixes`` branch of the media.git tree.
> > > +
> > > +Patches with fixes shall have:
> > > +
> > > +- a ``Fixes:`` tag pointing to the first commit that introduced the bug;
> > > +- when applicable, a ``Cc: stable@xxxxxxxxxxxxxxx``.
> > > +
> > > +Patches that were fixing bugs publicly reported by someone at the
> > > +linux-media@xxxxxxxxxxxxxxx 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|  
> > 
> > s/e-mail/LMML/
> 
> maybe, instead: e-mail to LMML.

Sounds good.

> 
> > (see earlier comment)? Same below.
> > 
> > > +     +------+   |picks it |   |request|   |in media-committers.git|   +---------+
> > > +                +---------+   +-------+   +-----------------------+
> > > +
> > > +   For this workflow, pull requests can be generated by a committer,
> > > +   a previous committer, subsystem maintainers or by a trusted long-time  
> > 
> > s/previous/former/
> > 
> > I'd also use plural in all cases here.
> 
> Ok.
> 
> > 
> > > +   contributor. 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|
> > > +     +------+   |picks it |   |media-committers.git|   |approval   |   +---------+
> > > +                +---------+   +--------------------+   +-----------+
> > > +
> > > +On both workflows, all patches shall be properly reviewed at
> > > +linux-media@xxxxxxxxxxxxxxx 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
> > > +explain why the errors are false positives.
> > > +
> > > +Patches will only be moved to the next stage in those two workflows if they
> > > +don't fail on CI or if there are false-positives in the CI reports.  
> > 
> > s/don't fail on/pass/
> 
> Ok.
> 
> > 
> > > +
> > > +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 +167,48 @@ 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 [2]_, 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\ [3]_ 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 a logic that checks if the
> > > +received e-mail contain a valid patch. Any whitespace and new line
> > > +breakages mangling the patch won't be recognized by patchwork, thus such
> > > +patch will be rejected.
> > > +
> > > +.. [2] 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.
> > > +
> > > +.. [3] 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 sign. 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 a PGP-signed tag.
> > >  
> > > -- Remote Controllers (infrared):
> > > -    Sean Young <sean@xxxxxxxx>
> > > +For more details about PGP sign, please read
> > > +Documentation/process/maintainer-pgp-guide.rst.  
> > 
> > s/.*/:ref:`the PGP guide <pgpguide>`/
> 
> No need. A Sphinx plugin does that automatically.

Ack.

> 
> > 
> > >  
> > > -- HDMI CEC:
> > > -    Hans Verkuil <hverkuil@xxxxxxxxx>
> > > +Subsystem maintainers
> > > +---------------------
> > >  
> > > -- Media controller drivers:
> > > -    Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
> > > -
> > > -- ISP, v4l2-async, v4l2-fwnode, v4l2-flash-led-class and Sensor drivers:
> > > -    Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
> > > -
> > > -- V4L2 drivers and core V4L2 frameworks:
> > > -    Hans Verkuil <hverkuil@xxxxxxxxx>
> > > -
> > > -The subsystem maintainer is:
> > > -  Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> > > -
> > > -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@xxxxxxxxxx> and
> > > +  - Hans Verkuil <hverkuil@xxxxxxxxx>
> > >  
> > >  Submit Checklist Addendum
> > >  -------------------------
> > > @@ -108,17 +225,14 @@ implementing the media APIs:
> > >  ====================	=======================================================
> > >  Type			Tool
> > >  ====================	=======================================================
> > > -V4L2 drivers\ [3]_	``v4l2-compliance``
> > > +V4L2 drivers\ [4]_	``v4l2-compliance``
> > >  V4L2 virtual drivers	``contrib/test/test-media``
> > >  CEC drivers		``cec-compliance``
> > >  ====================	=======================================================
> > >  
> > > -.. [3] The ``v4l2-compliance`` also covers the media controller usage inside
> > > +.. [4] 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.
> > > -
> > >  Those tests need to pass before the patches go upstream.
> > >  
> > >  Also, please notice that we build the Kernel with::
> > > @@ -134,6 +248,8 @@ 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 +315,7 @@ 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:``,
> > > diff --git a/MAINTAINERS b/MAINTAINERS
> > > index 1e930c7a58b1..c77f56a2e695 100644
> > > --- a/MAINTAINERS
> > > +++ b/MAINTAINERS
> > > @@ -14510,6 +14510,7 @@ MEDIA INPUT INFRASTRUCTURE (V4L/DVB)
> > >  M:	Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
> > >  L:	linux-media@xxxxxxxxxxxxxxx
> > >  S:	Maintained
> > > +P:	Documentation/driver-api/media/maintainer-entry-profile.rst
> > >  W:	https://linuxtv.org
> > >  Q:	http://patchwork.kernel.org/project/linux-media/list/
> > >  T:	git git://linuxtv.org/media.git  
> > 
> 
> 

-- 
Kind regards,

Sakari Ailus