From: Nishanth Menon <firstname.lastname@example.org>
To: Tony Lindgren <email@example.com>
Cc: Arnd Bergmann <firstname.lastname@example.org>,
Vignesh Raghavendra <email@example.com>,
Arnd Bergmann <firstname.lastname@example.org>, DTML <email@example.com>,
Lokesh Vutla <firstname.lastname@example.org>,
Dave Gerlach <email@example.com>, Sekhar Nori <firstname.lastname@example.org>,
Kishon Vijay Abraham <email@example.com>,
Rob Herring <firstname.lastname@example.org>,
Aswath Govindraju <email@example.com>,
Linux ARM <firstname.lastname@example.org>
Subject: Re: [PATCH v3 3/5] arm64: dts: ti: Add support for AM642 SoC
Date: Mon, 25 Jan 2021 08:16:42 -0600 [thread overview]
Message-ID: <20210125141642.4yybjnklk3qsqjdy@steersman> (raw)
On 15:00-20210122, Tony Lindgren wrote:
> * Arnd Bergmann <email@example.com> [210122 11:24]:
> > On Thu, Jan 21, 2021 at 8:57 PM Suman Anna <firstname.lastname@example.org> wrote:
> > > On 1/21/21 12:39 PM, Nishanth Menon wrote:
> > > > On 12:13-20210121, Suman Anna wrote:
> > > >>
> > > >> Hmm, this is kinda counter-intuitive. When I see a dts node, I am expecting the
> > > >
> > > > What is counter intutive about a -next branch be tested against
> > > > linux-next tree?
> > >
> > > The -next process is well understood. FWIW, you are not sending your PR against
> > > -next branch, but against primarily a -rc1 or -rc2 baseline.
> > >
> > > As a developer, when I am submitting patches, I am making sure that things are
> > > functional against the baseline you use. For example, when I split functionality
> > > into a driver portions and dts portions, I need to make sure both those
> > > individual pieces boot fine and do not cause regressions, even though for the
> > > final functionality, you need both.
> > > >
> > > >
> > > > Now, if you want to launch a product with my -next branch - go ahead, I
> > > > don't intent it for current kernel version - you are on your own.
> > > >
> > > > If there is a real risk of upstream next-breaking - speakup with an
> > > > real example - All I care about is keeping upstream functional and
> > > > useable.
> > >
> > > This is all moot when your own tree doesn't boot properly. In this case, you are
> > > adding MMC nodes, but yet for a boot test, you are saying use linux-next for the
> > > nodes that were added or you need additional driver patches (which is not how
> > > maintainer-level trees are verified).
> > >
> > > Arnd,
> > > Can you please guide us here as to what is expected in general, given that the
> > > pull-request from Nishanth goes through you, and if there is some pre-existing
> > > norms around this?
> > There are two very different cases to consider, and I'm not sure which one
> > we have here:
> > - When submitting any changes to a working platform, each patch on
> > a branch that gets merged needs to work incrementally, e.g. a device
> > tree change merged through the soc tree must never stop a platform
> > from booting without a patch that gets merged through another branch
> > in the same merge window, or vice versa.
> > As an extension of this, I would actually appreciate if we never do
> > incompatible binding changes at all. If a driver patch enables a new
> > binding for already supported hardware, a second patch changes
> > the dts file to use the new binding, and a third patch removes the
> > original binding, this could still be done without regressions over
> > multiple merge windows, but it breaks the assumption that a new
> > kernel can boot with an old dtb (or vice versa). This second one
> > is a softer requirement, and we can make exceptions for particularly
> > good reasons, but please explain those in the patch description and
> > discuss with upstream maintainers before submitting patches that do
> > this.
> > - For a newly added hardware support, having a runtime dependency
> > on another branch is not a problem, we do that all the time: Adding
> > a device node for an existing board (or a new board) and the driver
> > code in another branch is not a regression because each branch
> > only has incremental changes that improve hardware support, and
> > it will work as soon as both are merged.
> > You raised the point about device bindings, which is best addressed
> > by having one commit that adds the (reviewed) binding document
> > first, and then have the driver branch and the dts branch based on
> > the same commit.
> > I hope that clarifies the case you are interested in, let me know if I
> > missed something for the specific case at hand.
> Hmm and additionally few more mostly obvious things that have helped
> quite a bit:
> - Each commit in each topic branch should compile and boot so git
> bisect works
> - Each topic branch should be ideally based on -rc1 to leave out
> dependencies to other branches
> - Aiming for a working and usable -rc1 is worth the effort in case
> git bisect is needed for any top branches based on it :) Otherwise
> you'll be wasting the -rc cycle chasing regressions..
Thank you both for your valuable insight and direction. much
*) for every patch that is integrated - I already insist on
bisectability, no warnings with W=2 , dtbs_check .... Including
putting additional tooling in place for folks to use - which goes
and tests sparse, coccinelle etc.. The team has been pretty deligent
in making sure things are clean.
*) We also insist on testing with linux-next to maintain rc1
*) I also maintain the minimal boot requirements equivalent to kernelci
(example:) for my -next branch as well.
Yes, this series introduces 0 regression, new nodes are being added
and the thing I missed for this window, which is insisting on getting
immutable tags from subsystem maintainers for dt-bindings patches they
have picked up, will be rectified in the future. For this window,
for the last time, I am going to depend a bit on the later merge of
Thanks for the clarifications, once again.
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3 1A34 DDB5 849D 1736 249D
linux-arm-kernel mailing list
next prev parent reply other threads:[~2021-01-25 14:18 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-20 20:25 [PATCH v3 0/5] arm64: Initial support for Texas Instruments AM642 Platform Dave Gerlach
2021-01-20 20:25 ` [PATCH v3 1/5] dt-bindings: arm: ti: Add bindings for AM642 SoC Dave Gerlach
2021-01-20 20:25 ` [PATCH v3 2/5] dt-bindings: pinctrl: k3: Introduce pinmux definitions for AM64 Dave Gerlach
2021-01-20 20:50 ` Suman Anna
2021-01-25 14:39 ` Nishanth Menon
2021-02-09 2:34 ` Rob Herring
2021-01-20 20:25 ` [PATCH v3 3/5] arm64: dts: ti: Add support for AM642 SoC Dave Gerlach
2021-01-20 22:04 ` Nishanth Menon
2021-01-21 17:25 ` Suman Anna
2021-01-21 17:46 ` Nishanth Menon
2021-01-21 18:13 ` Suman Anna
2021-01-21 18:39 ` Nishanth Menon
2021-01-21 19:57 ` Suman Anna
2021-01-21 20:13 ` Nishanth Menon
2021-01-21 20:42 ` Suman Anna
2021-01-21 21:18 ` Nishanth Menon
2021-01-21 22:57 ` Suman Anna
2021-01-22 11:23 ` Arnd Bergmann
2021-01-22 13:00 ` Tony Lindgren
2021-01-25 14:16 ` Nishanth Menon [this message]
2021-01-25 22:48 ` Suman Anna
2021-01-25 23:02 ` Suman Anna
2021-01-20 20:25 ` [PATCH v3 4/5] arm64: dts: ti: k3-am64-main: Enable DMA support Dave Gerlach
2021-01-20 20:25 ` [PATCH v3 5/5] arm64: dts: ti: Add support for AM642 EVM Dave Gerlach
2021-01-25 16:44 ` Suman Anna
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