Author: Thomas Petazzoni

Thomas Petazzoni is Bootlin's co-owner and CEO. Thomas joined Bootlin in 2008 as a kernel and embedded Linux engineer, became CTO in 2013, and co-owner/CEO in 2021. More details...

Linux 4.10, Bootlin contributions

After 8 release candidates, Linus Torvalds released the final 4.10 Linux kernel last Sunday. A total of 13029 commits were made between 4.9 and 4.10. As usual, LWN had a very nice coverage of the major new features added during the 4.10 merge window: part 1, part 2 and part 3. The KernelNewbies Wiki has an updated page about 4.10 as well.

On the total of 13029 commits, 116 were made by Bootlin engineers, which interestingly is exactly the same number of commits we made for the 4.9 kernel release!

Our main contributions for this release have been:

  • For Atmel platforms, Alexandre Belloni added support for the securam block of the SAMA5D2, which is needed to implement backup mode, a deep suspend-to-RAM state for which we will be pushing patches over the next kernel releases. Alexandre also fixed some bugs in the Atmel dmaengine and USB gadget drivers.
  • For Allwinner platforms
    • Antoine Ténart enabled the 1-wire controller on the CHIP platform
    • Boris Brezillon fixed an issue in the NAND controller driver, that prevented from using ECC chunks of 512 bytes.
    • Maxime Ripard added support for the CHIP Pro platform from NextThing, together with many addition of features to the underlying SoC, the GR8 from Nextthing.
    • Maxime Ripard implemented audio capture support in the sun4i-i2s driver, bringing capture support to Allwinner A10 platforms.
    • Maxime Ripard added clock support for the Allwinner A64 to the sunxi-ng clock subsystem, and implemented numerous improvements for this subsystem.
    • Maxime Ripard reworked the pin-muxing driver on Allwinner platforms to use a new generic Device Tree binding, and deprecated the old platform-specific Device Tree binding.
    • Quentin Schulz added a MFD driver for the Allwinner A10/A13/A31 hardware block that provides ADC, touchscreen and thermal sensor functionality.
  • For the RaspberryPi platform
    • Boris Brezillon added support for the Video Encoder IP, which provides composite output. See also our recent blog post about our RaspberryPi work.
    • Boris Brezillon made a number of improvements to clock support on the RaspberryPi, which were needed for the Video Encoder IP support.
  • For the Marvell ARM platform
    • Grégory Clement enabled networking support on the Marvell Armada 3700 SoC, a Cortex-A53 based processor.
    • Grégory Clement did a large number of cleanups in the Device Tree files of Marvell platforms, fixing DTC warnings, and using node labels where possible.
    • Romain Perier contributed a brand new driver for the SPI controller of the Marvell Armada 3700, and therefore enabled SPI support on this platform.
    • Romain Perier extended the existing i2c-pxa driver to support the Marvell Armada 3700 I2C controller, and enabled I2C support on this platform.
    • Romain Perier extended the existing hardware number generator driver for OMAP to also be usable for SafeXcel EIP76 from Inside Secure. This allows to use this driver on the Marvell Armada 7K/8K SoC.
    • Romain Perier contributed support for the Globalscale EspressoBin board, a low-cost development board based on the Marvell Armada 3700.
    • Romain Perier did a number of fixes to the CESA driver, used for the cryptographic engine found on 32-bit Marvell SoCs, such as Armada 370, XP or 38x.
    • Thomas Petazzoni fixed a bug in the mvpp2 network driver, currently only used on Marvell Armada 375, but in the process of being extended to be used on Marvell Armada 7K/8K as well.
  • As the maintainer of the MTD NAND subsystem, Boris Brezillon did a few cleanups in the Tango NAND controller driver, added support for the TC58NVG2S0H NAND chip, and improved the core NAND support to accommodate controllers that have some special timing requirements.
  • As the maintainer of the RTC subsystem, Alexandre Belloni did a number of small cleanups and improvements, especially to the jz4740

Here is the detailed list of our commits to the 4.10 release:

Video and slides from Linux Conf Australia

Linux Conf Australia took place two weeks ago in Hobart, Tasmania. For the second time, a Bootlin engineer gave a talk at this conference: for this edition, Bootlin CTO Thomas Petazzoni did a talk titled A tour of the ARM architecture and its Linux support. This talk was intended as an introduction-level talk to explain what is ARM, what is the concept behind the ARM architecture and ARM System-on-chip, bootloaders typically used on ARM and the Linux support for ARM with the concept of Device Tree.

The slides of the talk are available in PDF format, and the video is available on Youtube. We got some nice feedback afterwards, which is a good indication a number of attendees found it informative.

All the videos from the different talks are also available on Youtube.

We once again found LCA to be a really great event, and want to thank the LCA organization for accepting our talk proposal and funding the travel expenses. Next year LCA, in 2018, will take place in Sydney, in mainland Australia.

Bootlin at FOSDEM and the Buildroot Developers Meeting

FOSDEM 2017Like every year, a number of Bootlin engineers will be attending the FOSDEM conference next week-end, on February 4 and 5, in Brussels. This year, Mylène Josserand and Thomas Petazzoni are going to FOSDEM. Being the biggest European open-source conference, FOSDEM is a great opportunity to meet a large number of open-source developers and learn about new projects.

In addition, Bootlin is sponsoring the participation of Thomas Petazzoni to the Buildroot Developers meeting, which takes place during two days right after the FOSDEM conference. During this event, the Buildroot developers community gathers to make progress on the project by having discussions on the current topics, and working on the patches that have been submitted and need to be reviewed and merged.

Bootlin at the Embedded Linux Conference 2017

The next Embedded Linux Conference will take place later this month in Portland (US), from February 21 to 23, with a great schedule of talks. As usual, a number of Bootlin engineers will attend this event, and we will also be giving a few talks.

Embedded Linux Conference 2017

Bootlin CEO Michael Opdenacker will deliver a talk on Embedded Linux size reduction techniques, while Bootlin engineer Quentin Schulz will give a talk on
Power Management Integrated Circuits: Keep the Power in Your Hands. In addition, Bootlin engineers Maxime Ripard, Antoine Ténart and Mylène Josserand will be attending the conference.

We once again look forward to meeting our fellow members of the embedded Linux and Linux kernel communities!

Linux 4.9 released, Bootlin contributions

Linus Torvalds has released the 4.9 Linux kernel yesterday, as was expected. With 16214 non-merge commits, this is by far the busiest kernel development cycle ever, but in large part due to the merging of thousands of commits to add support for Greybus. LWN has very well summarized what’s new in this kernel release: 4.9 Merge window part 1, 4.9 Merge window part 2, The end of the 4.9 merge window.

As usual, we take this opportunity to look at the contributions Bootlin made to this kernel release. In total, we contributed 116 non-merge commits. Our most significant contributions this time have been:

  • Bootlin engineer Boris Brezillon, already a maintainer of the Linux kernel NAND subsystem, becomes a co-maintainer of the overall MTD subsystem.
  • Contribution of an input ADC resistor ladder driver, written by Alexandre Belloni. As explained in the commit log: common way of multiplexing buttons on a single input in cheap devices is to use a resistor ladder on an ADC. This driver supports that configuration by polling an ADC channel provided by IIO.
  • On Atmel platforms, improvements to clock handling, bug fix in the Atmel HLCDC display controller driver.
  • On Marvell EBU platforms
    • Addition of clock drivers for the Marvell Armada 3700 (Cortex-A53 based), by Grégory Clement
    • Several bug fixes and improvements to the Marvell CESA driver, for the crypto engine founds in most Marvell EBU processors. By Romain Perier and Thomas Petazzoni
    • Support for the PIC interrupt controller, used on the Marvell Armada 7K/8K SoCs, currently used for the PMU (Performance Monitoring Unit). By Thomas Petazzoni.
    • Enabling of Armada 8K devices, with support for the slave CP110 and the first Armada 8040 development board. By Thomas Petazzoni.
  • On Allwinner platforms
    • Addition of GPIO support to the AXP209 driver, which is used to control the PMIC used on most Allwinner designs. Done by Maxime Ripard.
    • Initial support for the Nextthing GR8 SoC. By Mylène Josserand and Maxime Ripard (pinctrl driver and Device Tree)
    • The improved sunxi-ng clock code, introduced in Linux 4.8, is now used for Allwinner A23 and A33. Done by Maxime Ripard.
    • Add support for the Allwinner A33 display controller, by re-using and extending the existing sun4i DRM/KMS driver. Done by Maxime Ripard.
    • Addition of bridge support in the sun4i DRM/KMS driver, as well as the code for a RGB to VGA bridge, used by the C.H.I.P VGA expansion board. By Maxime Ripard.
  • Numerous cleanups and improvements commits in the UBI subsystem, in preparation for merging the support for Multi-Level Cells NAND, from Boris Brezillon.
  • Improvements in the MTD subsystem, by Boris Brezillon:
    • Addition of mtd_pairing_scheme, a mechanism which allows to express the pairing of NAND pages in Multi-Level Cells NANDs.
    • Improvements in the selection of NAND timings.

In addition, a number of Bootlin engineers are also maintainers in the Linux kernel, so they review and merge patches from other developers, and send pull requests to other maintainers to get those patches integrated. This lead to the following activity:

  • Maxime Ripard, as the Allwinner co-maintainer, merged 78 patches from other developers.
  • Grégory Clement, as the Marvell EBU co-maintainer, merged 43 patches from other developers.
  • Alexandre Belloni, as the RTC maintainer and Atmel co-maintainer, merged 26 patches from other developers.
  • Boris Brezillon, as the MTD NAND maintainer, merged 24 patches from other developers.

The complete list of our contributions to this kernel release:

Buildroot 2016.11 released, Bootlin contributions

Buildroot LogoThe 2016.11 release of Buildroot has been published on November, 30th. The release announcement, by Buildroot maintainer Peter Korsgaard, gives numerous details about the new features and updates brought by this release. This new release provides support for using multiple BR2_EXTERNAL directories, gives some important updates to the toolchain support, adds default configurations for 9 new hardware platforms, and 38 new packages were added.

On a total of 1423 commits made for this release, Bootlin contributed a total of 253 commits:

$ git shortlog -sn --author=free-electrons 2016.08..2016.11
   142  Gustavo Zacarias
   104  Thomas Petazzoni
     7  Romain Perier

Here are the most important contributions we did:

  • Romain Perier contributed a package for the AMD Catalyst proprietary driver. Such drivers are usually not trivial to integrate, so having a ready-to-use package in Buildroot will really make it easier for Buildroot users who use hardware with an AMD/ATI graphics controller. This package provides both the X.org driver and the OpenGL implementation. This work was sponsored by one of Bootlin customer.
  • Gustavo Zacarias mainly contributed a large set of patches that do a small update to numerous packages, to make sure the proper environment variables are passed. This is a preparation change to bring top-level parallel build in Buildroot. This work was also sponsored by another Bootlin customer.
  • Thomas Petazzoni did contributions in various areas:
    • Added a DEVELOPERS file to the tree, to reference which developers are interested by which architectures and packages. Not only it allows the developers to be Cc’ed when patches are sent on the mailing list (like the get_maintainers script does), but it also used by Buildroot autobuilder infrastructure: if a package fails to build, the corresponding developer is notified by e-mail.
    • Misc updates to the toolchain support: switch to gcc 5.x by default, addition of gcc patches needed to fix various issues, etc.
    • Numerous fixes for build issues detected by Buildroot autobuilders

In addition to contributing 104 commits, Thomas Petazzoni also merged 1095 patches from other developers during this cycle, in order to help Buildroot maintainer Peter Korsgaard.

Finally, Bootlin also sponsored the Buildroot project, by funding the meeting location for the previous Buildroot Developers meeting, which took place in October in Berlin, after the Embedded Linux Conference. See the Buildroot sponsors page, and also the report from this meeting. The next Buildroot meeting will take place after the FOSDEM conference in Brussels.

Bootlin at Linux.conf.au, January 2017

Linux.conf.au, which takes place every year in January in Australia or New Zealand, is a major event of the Linux community. Bootlin already participated to this event three years ago, and will participate again to this year’s edition, which will take place from January 16 to January 20 2017 in Hobart, Tasmania.

Linux Conf Australia 2017

This time, Bootlin CTO Thomas Petazzoni will give a talk titled A tour of the ARM architecture and its Linux support, in which he will share with LCA attendees what is the ARM architecture, how its Linux support is working, what the numerous variants of ARM processors and boards mean, what is the Device Tree, the ARM specific bootloaders, and more.

Linux.conf.au also features a number of other kernel related talks, such as the Kernel Report from Jonathan Corbet, Linux Kernel memory ordering: help arrives at last from Paul E. McKenney. The list of conferences is very impressive, and the event also features a number of miniconfs, including one on the Linux kernel.

If some of our readers located in Australia, New Zealand or neighboring countries plan on attending the conference, do not hesitate to drop us a mail so that we can meet during the event!

Slides and videos from the Embedded Linux Conference Europe 2016

Last month, the entire Bootlin engineering team attended the Embedded Linux Conference Europe in Berlin. The slides and videos of the talks have been posted, including the ones from the seven talks given by Bootlin engineers:

  • Alexandre Belloni presented on ASoC: Supporting Audio on an Embedded Board, slides and video.
  • Boris Brezillon presented on Modernizing the NAND framework, the big picture, slides and video.
  • Boris Brezillon, together with Richard Weinberger from sigma star, presented on Running UBI/UBIFS on MLC NAND, slides and video.
  • Grégory Clement presented on Your newer ARM64 SoC Linux check list, slides and video.
  • Thomas Petazzoni presented on Anatomy of cross-compilation toolchains, slides and video.
  • Maxime Ripard presented on Supporting the camera interface on the C.H.I.P, slides and video.
  • Quentin Schulz and Antoine Ténart presented on Building a board farm: continuous integration and remote control, slides and video.

Bootlin at the Kernel Recipes conference

Kernel RecipesThe 2016 edition of the Kernel Recipes conference will take place from September 28th to 30th in Paris. With talks from kernel developers Jonathan Corbet, Greg Kroah-Hartmann, Daniel Vetter, Laurent Pinchart, Tejun Heo, Steven Rosdedt, Kevin Hilman, Hans Verkuil and many others, the schedule looks definitely very appealing, and indeed the event is now full.

Thomas Petazzoni, Bootlin CTO, will be attending this event. If you’re interested in discussing business or career opportunities with Bootlin, this event will be a great place to meet together.

Bootlin at the X Developer Conference

The next X.org Developer Conference will take place on September 21 to September 23 in Helsinki, Finland. This is a major event for Linux developers working in the graphics/display areas, not only at the X.org level, but also at the kernel level, in Mesa, and other related projects.

Bootlin engineer Maxime Ripard will be attending this conference, with 80+ other engineers from Intel, Google, NVidia, Texas Instruments, AMD, RedHat, etc.

Maxime is the author of the DRM/KMS driver in the upstream Linux kernel for the Allwinner SoCs, which provides display support for numerous Allwinner platforms, especially Nextthing’s CHIP (with parallel LCD support, HDMI support, VGA support and composite video support). Maxime has also worked on making the 3D acceleration work on this platform with a mainline kernel, by adapting the Mali kernel driver. Most recently, Maxime has been involved in Video4Linux development, writing a driver for the camera interface of Allwinner SoCs, and supervising Florent Revest work on the Allwinner VPU that we published a few days ago.