Manivannan Sadhasivam leading discussion on PCI Endpoint open items: virtio, QEMU and more. Linux Plumbers Conference 2024 #LinuxPlumbers2024 #lpc2024 #linux
https://lpc.events/event/18/contributions/1683/

The Linux Plumbers Conference is just in three days and I am looking forward to it. I see plenty of interesting topics, so the conference looks promising. If Devicetree is something of interest for you, please come visit "Devicetree Birds of Feather" session on Friday morning:
https://lpc.events/event/18/contributions/1783/

P.S. If you want to grab a beer or chat, find me in the halls or get in touch via email/fedi. I won't be attending OSSE, though. Only Plumbers.

I’m happy to announce the Amlogic ARM64 Device Tree is now fully documented in linux-next, ready for v6.12!

Since the beginning of Device Tree on Linux, we documented how it should be written so drivers could know what to expect, it’s called “bindings”, it’s a sort of “contract” between Device Tree and drivers.

But those were written in human readable open text format, without any automated way to verify Device Tree files. There were numerous attempts, but ultimately Rob Herring leveraged JSON Schema [1] into “dtschema” [2] leading to this patch serie https://lore.kernel.org/all/20181005165848.3474-1-robh@kernel.org/.

Thus “dtschema” made it possible to write bindings in YAML and the developed scripts would convert Device Tree in YAML and run a validation with JSON Schema validation. This was merged in end of 2018 then conversion of the text files in YAML files started.

For reference, there were 3278 text bindings in Linux 4.20 git tree, in today’s Linux next for v6.12 only 1250 text files remains but there’s 4345 yaml files now! In addition to the transition to yaml bindings, new platforms were introduced using the new format.

Around one year ago, I upstreamed support for the Snapdragon 8 Gen 3, and it was fully documented from day 1, and most of the changes was yaml bindings change since the SoC was mainly an upgrade from the Snapdragon 8 Gen 2 I helped upstream 2 years ago.

Let’s go back to Amlogic, were I started converting the text file to yaml bindings in August 2019 (see [3]), and finally ended the transition early this month with the patch [4]. This makes the Amlogic ARM64 Device Trees join fully documented along other platforms like Samsung Exynos

If you want to know more about Device Tree validation, you can look at my @LinaroLtd colleague @krzk talk he did in this year's #EOSS in Seattle https://sched.co/1aBEf!

Now the links:
[1] https://json-schema.org/
[2] https://github.com/devicetree-org/dt-schema
[3] https://lore.kernel.org/all/20190801135644.12843-1-narmstrong@baylibre.com/
[4] https://lore.kernel.org/all/20240905-topic-amlogic-upstream-gxlx-drop-iio-compat-v2-1-7a690eb95bc2@linaro.org/
Thanks for reading !

U-Boot on Qualcomm Snapdragon platforms - great work, @calebccff !
https://www.linaro.org/blog/initial-u-boot-release-for-qualcomm-platforms/

@calebccff, Are these releases already using upstream/Linux kernel DTS? Looking at your qcom_defconfig, it seems answer is yes (OF_UPSTREAM)?

@kernellogger The problem is that Qualcomm ships devices with some weird ACPI tables which Linux simply cannot use. I don't know the details good enough to explain more. Maybe it would require rewriting several drivers to work with such Qcom-ACPI-variant.

RE: https://fosstodon.org/@kernellogger/112874114752280325

@mripard Nothing, but the topic shifted towards why usage of such laptops is non-trivial in the beginning.

RE: https://fosstodon.org/@mripard/112874339733019220

@kernellogger It boils down whether ACPI is properly implemented on given platform. There are ARM64 platforms running correctly under ACPI, e.g. most of the ARM64 servers, and you don't care about such differences.
The trouble starts when ACPI is not there (so almost all embedded designs, mobile phones/tables) or ACPI is somehow botched (e.g. Qualcomm Snapdragon compute platforms and laptops based on it), because then you go with Devicetree/DTS and everything starts... But such platforms are not consumer devices, usually. And really the Qualcomm Snapdragon for laptops should have just used ACPI.

RE: https://fosstodon.org/@kernellogger/112871174600451364

A video directly confirms a Russian missile strike on "Okhmatdyt" in Kyiv. It wasn't intercepted and didn't deviate from its coordinates - it was aimed precisely there to cause maximum casualties and inflict the most pain.

SBU investigators have determined that Russia struck "Okhmatdyt" with a Kh-101 missile.

#RussiaIsATerroristState #ArmUkraineNow #Ukraine #EU #Europe #NATOSummit #NatoAllies

Since a year we got some contributions for converting Devicetree bindings from TXT to DT schema as part of some sort mentorship programs. This is great although leads to some misunderstandings in that work, considering mentorships did not ask DT maintainers about some sort of guidance. To clarify:

1. Please convert bindings which have active DTS users. First choose bindings with DTS built by arm64 defconfig, then next choice by arm multi_v7 defconfig. Then any other ARM or different architecture DTS.

2. Be sure dt_bindings_check (including yamllint) and checkpatch pass without any warnings. See writing-schema.rst document.

3. Be sure DTS using this binding passes dtbs_check validation. If this means binding needs to be adapted during conversion, mention briefly in commit message changes done comparing to pure TXT->DT schema conversion. Sometimes DTS has to be fixed. Sometimes both - DTS and binding - must be changed, because actual ABI (Linux drivers) is different.

That's an interesting session: @cas explaining current status of upstream U-Boot on Qualcomm robotic platforms - using mainline kernel DTS and getting to SystemReady IR.
Slides: https://calebs.dev/u-boot24.pdf
https://www.kitefor.events/events/linaro-connect-24/submissions/183

@abelvesa explaining the hacking setup used during his bringing up of the Qualcomm X Elite compute platform in Linaro:
https://www.kitefor.events/events/linaro-connect-24/submissions/182

Just a reminder: only a week to hear me babbling about Linux kernel DTS validation and shared reset GPIOs on Embedded Open Source Summit/OSSNA 2024. Don't miss it and come to say hi!
EOSS: https://sched.co/1aBEf
OSSNA: https://sched.co/1aPvr

Hey, Google, not again! How am I supposed to send my patches?

smtplib.SMTPDataError: 5.4.5 Daily user sending limit exceeded.

Preparing speeches for conferences was always rather difficult for me. Went slow, somehow painful. But now I have wonderful data, which I am going to present, and it is just pleasure to write the slides slowly reaching the conclusion I want to share!
https://sched.co/1aBEf

Thanks Pope for making me angry enough! Don't like your fundraising campaign style, but it worked! #DronesNotWhiteFlags

If you ever wondered how Linux kernel can handle multiple devices sharing the same GPIO, you got one more reason to go to Seattle this April:
https://sched.co/1aPvr

My second talk got accepted to LinuxCon / Open Source Summit NA 2024.

About current EU and Polish farmer protests, let's digest this meme. Left pic is from Poland, where Polish farmers protest with Soviet Union flag and banner saying:
"Puting clean up mess with Ukraine, Brussels and our government."

Right picture is from Ukraine (quite old btw)...

In the face of hundreds of thousands murdered in Ukraine, and millions more displaced fleeing Russian military aggression, it is hard to focus on the death of one man. And yet, Navalny meant a lot to the Russian opposition and his death is just another proof that Putin's regime is criminal to the core and cannot be dealt with by appeasement or backroom deals. Ukrainians are the only force actively fighting the Kremlin mafia regime and we should continue to give them all they need to achieve a swift and decisive victory.

Is DT schema validation of DTS boards helpful or not? Get ready to find it out during my talk on EOSS 2024 conference in April:
https://sched.co/1aBEf
See you in Seattle!

10 years ago I sent a patch to fix one compatible in one Marvell SoC board:
https://lore.kernel.org/linux-devicetree/1410884282-18041-1-git-send-email-k.kozlowski@samsung.com/
Obvious fix but was never picked up.

In 2021 Sebastian tried to fix it:
https://lore.kernel.org/linux-devicetree/20210412230320.382885-2-sebastian.reichel@collabora.com/

Now in 2023 and 2024, Duje tries the same:
https://lore.kernel.org/linux-devicetree/20240125-brownstone-typo-fix-v2-1-45bc48a0c81c@skole.hr/

Will it succeed?