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Linux Kernel developer and maintainer
🇵🇱 🇪🇺 🇰🇷 🇮🇱 🇺🇦 🇨🇭
IRC: krzk
Kernel work related account. Other accounts of mine: @krzk@mastodon.social

Krzysztof Kozlowski

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)?
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Krzysztof Kozlowski

@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
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Krzysztof Kozlowski

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

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

@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
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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
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Krzysztof Kozlowski

Edited 3 months ago
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.
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Krzysztof Kozlowski

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
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Krzysztof Kozlowski

Edited 3 months ago
@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
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Krzysztof Kozlowski

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
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Krzysztof Kozlowski

Edited 5 months ago

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

smtplib.SMTPDataError: 5.4.5 Daily user sending limit exceeded.

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Krzysztof Kozlowski

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
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Vlastimil Babka

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

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.
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Krzysztof Kozlowski

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)...
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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.
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Krzysztof Kozlowski

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!
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Krzysztof Kozlowski

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?
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Krzysztof Kozlowski

Linux v6.8-rc1 comes with new document describing coding style for DTS (Devicetree sources):
https://www.kernel.org/doc/html/latest/devicetree/bindings/dts-coding-style.html

This marks the end of many unwritten rules, varying between subsystems and maintainers. At least, like with every coding style document, in theory. :)
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Krzysztof Kozlowski

Edited 8 months ago
I was always using git branch --edit-description && git format-patch && git send-email, but now I tried preparing and sending patchset with b4 (b4 prep && b4 send). It works great! It is trivial in use and really solves the workflow. I cannot understand why people still Cc wrong people or are unable to send one patchset properly threaded.

Edit: --edit-cover->--edit-description
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FYI, Qualcomm Snapdragon X Elite (X1E80100) now boots to shell with today's -next.

More support is already sent on the list for review:
https://lore.kernel.org/all/?q=X1E80100

And here is a public branch with all support currently available on top of -next:
https://git.codelinaro.org/abel.vesa/linux/-/tree/x1e80100-next
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