Linux 4.11, Bootlin contributions

Linus Torvalds has released this Sunday Linux 4.11. For an overview of the new features provided by this new release, one can read the coverage from LWN: part 1, part 2 and part 3. The KernelNewbies site also has a detailed summary of the new features.

With 137 patches contributed, Bootlin is the 18th contributing company according to the Kernel Patch Statistics. Bootlin engineer Maxime Ripard appears in the list of top contributors by changed lines in the LWN statistics.

Our most important contributions to this release have been:

  • Support for Atmel platforms
    • Alexandre Belloni improved suspend/resume support for the Atmel watchdog driver, I2C controller driver and UART controller driver. This is part of a larger effort to upstream support for the backup mode of the Atmel SAMA5D2 SoC.
    • Alexandre Belloni also improved the at91-poweroff driver to properly shutdown LPDDR memories.
    • Boris Brezillon contributed a fix for the Atmel HLCDC display controller driver, as well as fixes for the atmel-ebi driver.
  • Support for Allwinner platforms
    • Boris Brezillon contributed a number of improvements to the sunxi-nand driver.
    • Mylène Josserand contributed a new driver for the digital audio codec on the Allwinner sun8i SoC, as well a the corresponding Device Tree changes and related fixes. Thanks to this driver, Mylène enabled audio support on the R16 Parrot and A33 Sinlinx boards.
    • Maxime Ripard contributed numerous improvements to the sunxi-mmc MMC controller driver, to support higher data rates, especially for the Allwinner A64.
    • Maxime Ripard contributed official Device Tree bindings for the ARM Mali GPU, which allows the GPU to be described in the Device Tree of the upstream kernel, even if the ARM kernel driver for the Mali will never be merged upstream.
    • Maxime Ripard contributed a number of fixes for the rtc-sun6i driver.
    • Maxime Ripard enabled display support on the A33 Sinlinx board, by contributing a panel driver and the necessary Device Tree changes.
    • Maxime Ripard continued his clean-up effort, by converting the GR8 and sun5i clock drivers to the sunxi-ng clock infrastructure, and converting the sun5i pinctrl driver to the new model.
    • Quentin Schulz added a power supply driver for the AXP20X and AXP22X PMICs used on numerous Allwinner platforms, as well as numerous Device Tree changes to enable it on the R16 Parrot and A33 Sinlinx boards.
  • Support for Marvell platforms
    • Grégory Clement added support for the RTC found in the Marvell Armada 7K and 8K SoCs.
    • Grégory Clement added support for the Marvell 88E6141 and 88E6341 Ethernet switches, which are used in the Armada 3700 based EspressoBin development board.
    • Romain Perier enabled the I2C controller, SPI controller and Ethernet switch on the EspressoBin, by contributing Device Tree changes.
    • Thomas Petazzoni contributed a number of fixes to the OMAP hwrng driver, which turns out to also be used on the Marvell 7K/8K platforms for their HW random number generator.
    • Thomas Petazzoni contributed a number of patches for the mvpp2 Ethernet controller driver, preparing the future addition of PPv2.2 support to the driver. The mvpp2 driver currently only supports PPv2.1, the Ethernet controller used on the Marvell Armada 375, and we are working on extending it to support PPv2.2, the Ethernet controller used on the Marvell Armada 7K/8K. PPv2.2 support is scheduled to be merged in 4.12.
  • Support for RaspberryPi platforms
    • Boris Brezillon contributed Device Tree changes to enable the VEC (Video Encoder) on all bcm283x platforms. Boris had previously contributed the driver for the VEC.

In addition to our direct contributions, a number of Bootlin engineers are also maintainers of various subsystems in the Linux kernel. As part of this maintenance role:

  • Maxime Ripard, co-maintainer of the Allwinner ARM platform, reviewed and merged 85 patches from contributors
  • Alexandre Belloni, maintainer of the RTC subsystem and co-maintainer of the Atmel ARM platform, reviewed and merged 60 patches from contributors
  • Grégory Clement, co-maintainer of the Marvell ARM platform, reviewed and merged 42 patches from contributors
  • Boris Brezillon, maintainer of the MTD NAND subsystem, reviewed and merged 8 patches from contributors

Here is the detailed list of contributions, commit per commit:

Bootlin contributions to Linux 4.5

Adelie PenguinLinus Torvalds just released Linux 4.5, for which the major new features have been described by LWN.net in three articles: part 1, part 2 and part 3. On a total of 12080 commits, Bootlin contributed 121 patches, almost exactly 1% of the total. Due to its large number of contribution by patch number, Bootlin engineer Boris Brezillon appears in the statistics of top-contributors for the 4.5 kernel in the LWN.net statistics article.

This time around, our important contributions were:

  • Addition of a driver for the Microcrystal rv1805 RTC, by Alexandre Belloni.
  • A huge number of patches touching all NAND controller drivers and the MTD subsystem, from Boris Brezillon. They are the first step of a more general rework of how NAND controllers and NAND chips are handled in the Linux kernel. As Boris explains in the cover letter, his series aims at clarifying the relationship between the mtd and nand_chip structures and hiding NAND framework internals to NAND. […]. This allows removal of some of the boilerplate code done in all NAND controller drivers, but most importantly, it unifies a bit the way NAND chip structures are instantiated.
  • On the support for the Marvell ARM processors:
    • In the mvneta networking driver (used on Armada 370, XP, 38x and soon on Armada 3700): addition of naive RSS support with per-CPU queues, configure XPS support, numerous fixes for potential race conditions.
    • Fix in the Marvell CESA driver
    • Misc improvements to the mv_xor driver for the Marvell XOR engines.
    • After four years of development the 32-bits Marvell EBU platform support is now pretty mature and the majority of patches for this platform now are improvements of existing drivers or bug fixes rather than new hardware support. Of course, the support for the 64-bits Marvell EBU platform has just started, and will require a significant number of patches and contributions to be fully supported upstream, which is an on-going effort.
  • On the support for the Atmel ARM processors:
    • Addition of the support for the L+G VInCo platform.
    • Improvement to the macb network driver to reset the PHY using a GPIO.
    • Fix Ethernet PHY issues on Atmel SAMA5D4
  • On the support for Allwinner ARM processors:
    • Implement audio capture in the sun4i audio driver.
    • Add the support for a special pin controller available on Allwinner A80.

The complete list of our contributions:

Linux 4.4, Bootlin contributions

Linux 4.4 is the latest releaseLinux 4.4 has been released, a week later than the normal schedule in order to allow kernel developers to recover from the Christmas/New Year period. As usual, LWN has covered the 4.4 cycle merge window, in two articles: part 1 and part 2. This time around, KernelNewbies has a nice overview of the Linux 4.4 changes. With 112 patches merged, we are the 20th contributing company by number of patches according to the statistics.

Besides our contributions in terms of patches, some of our engineers have also become over time maintainers of specific areas of the Linux kernel. Recently, LWN.net conducted a study of how the patches merged in 4.4 went into the kernel, which shows the chain of maintainers who pushed the patches up to Linus Torvalds. Bootlin engineers had the following role in this chain of maintainers:

  • As a co-maintainer of the Allwinner (sunxi) ARM support, Maxime Ripard has submitted a pull request with one patch to the clock maintainers, and pull requests with a total of 124 patches to the ARM SoC maintainers.
  • As a maintainer of the RTC subsystem, Alexandre Belloni has submitted pull requests with 30 patches directly to Linus Torvalds.
  • As a co-maintainer of the AT91 ARM support, Alexandre Belloni has submitted pull requests with 46 patches to the ARM SoC maintainers.
  • As a co-maintainer of the Marvell EBU ARM support, Gregory Clement has submitted pull requests with a total of 33 patches to the ARM SoC maintainers.

Our contributions for the 4.4 kernel were centered around the following topics:

  • Alexandre Belloni continued some general improvements to support for the AT91 ARM processors, with fixes and cleanups in the at91-reset, at91-poweroff, at91_udc, atmel-st, at91_can drivers and some clock driver improvements.
  • Alexandre Belloni also wrote a driver for the RV8803 RTC from Microcrystal.
  • Antoine Ténart added PWM support for the Marvell Berlin platform and enabled the use of cpufreq on this platform.
  • Antoine Ténart did some improvements in the pxa3xx_nand driver, still in preparation to the addition of support for the Marvell Berlin NAND controller.
  • Boris Brezillon did a number of improvements to the sunxi_nand driver, used for the NAND controller found on the Allwinner SoCs. Boris also merged a few patches doing cleanups and improvements to the MTD subsystem itself.
  • Boris Brezillon enabled the cryptographic accelerator on more Marvell EBU platforms by submitting the corresponding Device Tree descriptions, and he also fixed a few bugs found in the driver
  • Maxime Ripard reworked the interrupt handling of per-CPU interrupts on Marvell EBU platforms especially in the mvneta network driver. This was done in preparation to enable RSS support in the mvneta driver.
  • Maxime Ripard added support for the Allwinner R8 and the popular C.H.I.P platform.
  • Maxime Ripard enabled audio support on a number of Allwinner platforms, by adding the necessary clock code and Device Tree descriptions, and also several fixes/improvements to the ALSA driver.

The details of our contributions for 4.4:

Linux 4.1 released, Bootlin 17th contributing company

TuxLinus Torvalds recently released the 4.1 Linux kernel, for which LWN.net gave a good description of the major new features: 4.1 Merge window, part 1, 4.1 Merge window, part 2, The 4.1 merge window closes.

As usual, Bootlin engineers contributed to the Linux kernel during this development cycle, though this time with a smaller number of patches: we contributed 118 patches. This time around, Bootlin is the 17th company contributing to this kernel release, by number of patches.

Our major contributions this time around have been:

  • On support for Atmel platforms
    • Alexandre Belloni did a good number of improvements to Atmel SoC support: converting some remaining SoCs to the SoC detection infrastructure, cleaning up the timer driver to use a syscon/regmap, removing a lot of unused headers in arch/arm/mach-at91/, etc. The final and very important change is that the AT91 ARM platform is now part of the multiplatform mechanism: you can build a single zImage for ARMv5 or for ARMv7 which will include support for the ARMv5 or ARMv7 Atmel platforms.
    • Boris Brezillon improved the Atmel DRM/KMS driver for the display controller by switching to atomic mode-setting. He also added Device Tree definitions for the Atmel display controller on Atmel SAMA5D3 and Atmel SAMA5D4.
  • On support for Marvell EBU platforms
    • Ezequiel Garcia enabled the Performance Monitor Unit on Armada 375 and Armada 38x, which allows to use perf on those platforms.
    • Gregory Clement did a number of fixes and minor improvements to support for Marvell EBU platforms.
    • Maxime Ripard enabled the Performance Monitoring Unit on Armada 370/XP, enabling the use of perf on these platforms. He also improved support for the Armada 385 AP board by enabling NAND and USB3 support.
    • Thomas Petazzoni added initial support for the new Marvell Armada 39x platform (clock driver, pinctrl driver, Device Tree). He did some cleanup and fixes in many Device Tree of Marvell EBU platforms and added suspend/resume support in the PCI and pinctrl drivers for these platforms.
  • Other contributions
    • As we posted recently, Alexandre Belloni also became in this release cycle a co-maintainer for the RTC subsystem.
    • Alexandre Belloni added bq27510 support for the bq27x00_battery driver.
    • Maxime Ripard did some small contributions to the dmaengine subsystem, improved the of_touchscreen code and the edt-ft5x06 touchscreen driver, and did some cleanup in the Allwinner sun5i clocksource driver.

For the upcoming 4.2 version, we have 198 patches in linux-next, of which 191 have already been pulled by Linus as part of the 4.2 merge window.

Our complete list of contributions follows:

Buildroot 2015.05 release, Bootlin contributions inside

Buildroot LogoThe Buildroot project has recently released a new version, 2015.05. With exactly 1800 patches, it’s the largest release cycle ever, with patches from more than 100 different contributors. It’s an impressive number, showing the growing popularity of Buildroot as an embedded Linux build system.

The CHANGES file summarizes the most important improvements of this release.

Amongst those 1800 patches, 143 patches were contributed by Bootlin. Our most significant contributions for this release have been:

  • Addition of a package for the wf111 WiFi drivers. They allow to use a WiFi chip from Bluegiga, which is being used in one of our customer projects.
  • Addition of the support for using uClibc-ng. uClibc-ng is a “collaborative” fork of the uClibc project, which aims at doing more regular releases and have better testing. Maintained by Waldemar Brodkorb, the project has already seen several releases since its initial 1.0 release. Waldemar is merging patches from the original uClibc regularly, and adding more fixes. It allows Buildroot and other uClibc users to have well-identified uClibc stable versions instead of a 3 years old 0.9.33.2 version with dozens of patches on top of it. uClibc-ng is not currently used as the default uClibc version as of 2015.05, but it might very well be the case in 2015.08.
  • Important internal changes to the core infrastructure. Until this release, the make legal-info, make source, make external-deps and make source-check logic was relying only on the Buildroot configuration file. This was giving correct results for target packages which all have a corresponding Buildroot configuration option, but not for host packages (which for most of them don’t have Buildroot configuration options). Only a manual two-level dependency handling was done for the host packages for the above mentioned commands. With our work, the handling of those features has been moved to be part of the package infrastructure itself, so it’s using proper make recursivity to resolve the entire dependency tree. Due to this, the results of make legal-info or make external-deps may be longer following this release, but it’s because it’s now actually correct and complete. You can look at the patches for more details, but these changes are very deep into the core Buildroot infrastructure.
  • Large number of build fixes. We contributed 52 patches fixing issues detected by the autobuild infrastructure.
  • Addition of the imx-usb-loader package, which can be used to load over USB a new bootloader on i.MX6 platforms, even if the platform has no bootloader or a broken bootloader. We also use it as part of one of our customer projects.

With 142 patches, Bootlin engineer Thomas Petazzoni is the third contributor to this release by number of patches:

git shortlog -s -n 2015.02..

   397	Bernd Kuhls
   393	Gustavo Zacarias
   142	Thomas Petazzoni

But by far, our most important contribution by far for this release is Thomas acting as the interim maintainer: on the total of 1800 patches merged for this release, Thomas has been the committer of 1446 patches. He has therefore been very active in merging the patches contributed by the Buildroot community.

There are already some very interesting goals set for the Buildroot 2015.08 release, as you can see on the Buildroot release goals page.

Also, if you want to learn Buildroot in details, do not hesitate to look at our Buildroot training course!