Free seats in embedded Linux and kernel training sessions (Mar 2019)

Student penguinsAt Bootlin, we owe a lot to the Free Software community, and we’re doing our best to give back as much as we can.

One way of doing that is welcoming community contributors in our public training sessions organized in France. We’ve done that multiple times several years back, and this allowed us to meet very interesting people (who even had very valuable experience and points of view to share with the other course participants), while of course giving them extra knowledge that they can use for further contributions.

Here are the next sessions in which we can offer a free seat:

See our Free training seats page for practical details about how to apply.

Don’t hesitate to apply to this free seat. In past editions, we didn’t have so many people applying, and therefore you have a real chance to get selected!

Linux 4.19 released, Bootlin contributions

Penguin from Mylène Josserand
Drawing from Mylène Josserand,
based on a picture from Samuel Blanc under CC-BY-SA

With the 4.19 released last week by Greg Kroah-Hartman (and not Linus), it’s time to have a look at our contributions for this release.

As always, LWN.net did an interesting coverage of this release cycle merge window, highlighting the most important changes: the first half of the 4.19 merge window and the rest of the 4.19 merge window. For 4.19 only, Bootlin contributed a total of 295 patches, which puts us at the 10th place in the ranking of most contributing companies according to KPS.

Also according to LWN statistics, Bootlin’s engineer Boris Brezillon is the 16th most active developer in terms of commits for this release with a total of 85.

The main highlights of our contributions are:

Bootlin engineers are not only contributors, but also maintainers of various subsystems in the Linux kernel, which means they are involved in the process of reviewing, discussing and merging patches contributed to those subsystems:

  • Maxime Ripard, as the Allwinner platform co-maintainer, merged 93 patches from other contributors
  • Boris Brezillon, as the MTD/NAND maintainer, merged 38 patches from other contributors
  • Miquèl Raynal, as the NAND co-maintainer, merged 110 patches from other contributors
  • Alexandre Belloni, as the RTC and Microsemi maintainer and Atmel platform co-maintainer, merged 38 patches from other contributors
  • Grégory Clement, as the Marvell EBU co-maintainer, merged 16 patches from other contributors

Here is the commit by commit detail of our contributions to 4.19:

Linux 4.15 released, Bootlin contributions

Penguin from Mylène Josserand
Drawing from Mylène Josserand,
based on a picture from Samuel Blanc under CC-BY-SA

After a month of February busier than usual, with the renaming of our company from Free Electrons to Bootlin, our participation to FOSDEM and the welcoming of Maxime Chevallier, the latest addition to our engineering team, our article on the latest release of the Linux kernel arrives a bit late, more than a month after Linux 4.15 has been released by Linus Torvalds.

As usual, LWN.net did an interesting coverage of this release cycle merge window, highlighting the most important changes: The first half of the 4.15 merge window and The rest of the 4.15 merge window. Due to the now well-known Spectre and Meltdown vulnerabilities and the resulting effort to try to mitigate them, 4.15 required a -rc9, which happened the last time back in 2011 with the 3.1, Torvalds said.

According to Linux Kernel Patch statistics, Bootlin (now Bootlin) contributed 150 patches to this release, making it the 16th contributing company by number of commits.

The main highlights of our contributions are:

  • In the RTC subsystem, Alexandre Belloni made a number of improvements to various drivers, mainly making them use the nvmem subsystem where appropriate, and use the recently introduced rtc_register_device() API.
  • In the MTD subsystem, both Boris Brezillon and Miquèl Raynal made a number of contributions, mainly fixes.
  • For Marvell platforms
    • Antoine Ténart contributed a few fixes to the inside-secure crypto accelerator driver, used on Marvell Armada 3700 and Armada 7K/8K
    • Antoine Ténart also contributed fixes and improvements to the mvpp2 network driver, used for the Ethernet controller on the Marvell Armada 7K/8K. His improvements include preparation work to support Receive Side Scaling (RSS).
    • Antoine Ténart enabled more networking ports and features in some Armada 7K/8K boards, especially SFP ports on Armada 7040 DB and Armada 7040 DB.
    • Boris Brezillon contributed a few fixes to the Marvell CESA crypto accelerator driver, used on the older Orion, Kirkwood, Armada 370/XP/38x processors. He migrated the driver to use the skcipher interface of the Linux kernel crypto framework.
    • Grégory Clement enabled NAND support on Armada 7K, and contributed a number of fixes around MMC support for some Marvell boards.
    • Thomas Petazzoni contributed a few minor Device Tree enhancements for Marvell platforms: fixing MPP muxing on an older Kirkwood platform, enabling more PCIe ports on Armada 8040 DB, etc.
    • Miquèl Raynal contributed support for more advanced statistics in the mvpp2 network driver.
    • Miquèl Raynal added support for the extended UART for the Marvell Armada 3720 processor, both in the UART driver and in the Device Tree.
  • For the RaspberryPi platform, Boris Brezillon contributed a few fixes to the vc4 display driver, and added support for the new DRM_IOCTL_VC4_GEM_MADVISE ioctl, which can be used to ask the userspace applications to purge inactive buffers when allocations start to fail in the kernel.
  • For Allwinner platforms
    • Mylène Josserand contributed a fix for the Allwinner A83 clock driver, fixing I2C bus clocks.
    • Quentin Schulz contributed a few fixes to the sun4i-gpadc-iio.c driver, which is used for the ADCs on several Allwinner processors.
    • Maxime Ripard made a number of fixes to the sun8i-codec driver, fixing clock issues, left/right channels inversion, etc.
    • Maxime Ripard made a number of improvements to the sun4i DRM display driver.
    • Maxime Ripard improved the support for the A83 processor (described the UART1 controller, the MMC1 controller, added support for display clocks) and added the Device Tree for a new A83 device.
    • Maxime Ripard also did a number of cleanups and misc improvements in a significant number of Device Tree files for Allwinner platforms.
  • Thomas Petazzoni made a few fixes to the sh_eth network driver, used on several Renesas SuperH platform, as part of a recent project Bootlin did on SuperH 4.

Bootlin engineers are not only contributors, but also maintainers of various subsystems in the Linux kernel, which means they are involved in the process of reviewing, discussing and merging patches contributed to those subsystems:

  • Maxime Ripard, as the Allwinner platform co-maintainer, merged 108 patches from other contributors
  • Boris Brezillon, as the MTD/NAND maintainer, merged 34 patches from other contributors
  • Alexandre Belloni, as the RTC maintainer and Atmel platform co-maintainer, merged 50 patches from other contributors
  • Grégory Clement, as the Marvell EBU co-maintainer, merged 24 patches from other contributors

Here is the commit by commit detail of our contributons to 4.15:

Linux 4.13 released, Bootlin contributions

Linux 4.13 was released last Sunday by Linus Torvalds, and the major new features of this release were described in details by LWN in a set of articles: part 1 and part 2.

This release gathers 13006 non-merge commits, amongst which 239 were made by Bootlin engineers. According to the LWN article on 4.13 statistics, this makes Bootlin the 13th contributing company by number of commits, the 10th by lines changed.

The most important contributions from Bootlin for this release have been:

  • In the RTC subsystem
    • Alexandre Belloni introduced a new method for registering RTC devices, with one step for the allocation, and one step for the registration itself, which allows to solve race conditions in a number of drivers.
    • Alexandre Belloni added support for exposing the non-volatile memory found in some RTC devices through the Linux kernel nvmem framework, making them usable from userspace. A few drivers were changed to use this new mechanism.
  • In the MTD/NAND subsystem
    • Boris Brezillon did a large number of fixes and minor improvements in the NAND subsystem, both in the core and in a few drivers.
    • Thomas Petazzoni contributed the support for on-die ECC, specifically with Micron NANDs. This allows to use the ECC calculation capabilities of the NAND chip itself, as opposed to using software ECC (calculated by the CPU) or ECC done by the NAND controller.
    • Thomas Petazzoni contributed a few improvements to the FSMC NAND driver, used on ST Spear platforms. The main improvement is to support the ->setup_data_interface() callback, which allows to configure optimal timings in the NAND controller.
  • Support for Allwinner ARM platforms
    • Alexandre Belloni improved the sun4i PWM driver to use the so-called atomic API and support hardware read out.
    • Antoine Ténart improved the sun4i-ss cryptographic engine driver to support the Allwinner A13 processor, in addition to the already supported A10.
    • Maxime Ripard contributed HDMI support for the Allwinner A10 processor (in the DRM subsystem) and a number of related changes to the Allwinner clock support.
    • Quentin Schulz improved the support for battery charging through the AXP20x PMIC, used on Allwinner platforms.
  • Support for Atmel ARM platforms
    • Alexandre Belloni added suspend/resume support for the Atmel SAMA5D2 clock driver. This is part of a larger effort to implement the backup mode for the SAMA5D2 processor.
    • Alexandre Belloni added suspend/resume support in the tcb_clksrc driver, used as for clocksource and clockevents on Atmel SAMA5D2.
    • Alexandre Belloni cleaned up a number of drivers, removing support for non-DT probing, which is possible now that the AVR32 architecture has been dropped. Indeed, the AVR32 processors used to share the same drivers as the Atmel ARM processors.
    • Alexandre Belloni added the core support for the backup mode on Atmel SAMA5D2, a suspend/resume state with significant power savings.
    • Boris Brezillon switched Atmel platforms to use the new binding for the EBI and NAND controllers.
    • Boris Brezillon added support for timing configuration in the Atmel NAND driver.
    • Quentin Schulz added suspend/resume support to the Bosch m_can driver, used on Atmel platforms.
  • Support for Marvell ARM platforms
    • Antoine Ténart contributed a completely new driver (3200+ lines of code) for the Inside Secure EIP197 cryptographic engine, used in the Marvell Armada 7K and 8K processors. He also subsequently contributed a number of fixes and improvements for this driver.
    • Antoine Ténart improved the existing mvmdio driver, used to communicate with Ethernet PHYs over MDIO on Marvell platforms to support the XSMI variant found on Marvell Armada 7K/8K, used to communicate with 10G capable PHYs.
    • Antoine Ténart contributed minimal support for 10G Ethernet in the mvpp2 driver, used on Marvell Armada 7K/8K. For now, the driver still relies on low-level initialization done by the bootloader, but additional changes in 4.14 and 4.15 will remove this limitation.
    • Grégory Clement added a new pinctrl driver to configure the pin-muxing on the Marvell Armada 37xx processors.
    • Grégory Clement did a large number of changes to the clock drivers used on the Marvell Armada 7K/8K processors to prepare the addition of pinctrl support.
    • Grégory Clement added support for Marvell Armada 7K/8K to the existing mvebu-gpio driver.
    • Thomas Petazzoni added support for the ICU, a specialized interrupt controller used on the Marvell Armada 7K/8K, for all devices located in the CP110 part of the processor.
    • Thomas Petazzoni removed a work-around to properly resume per-CPU interrupts on the older Marvell Armada 370/XP platforms.
  • Support for RaspberryPi platforms
    • Boris Brezillon added runtime PM support to the HDMI encoder driver used on RaspberryPi platforms, and contributed a few other fixes to the VC4 DRM driver.

It is worth mentioning that Miquèl Raynal, recently hired by Bootlin, sees his first kernel patch merged: nand: fix wrong default oob layout for small pages using soft ecc.

Bootlin engineers are not only contributors, but also maintainers of various subsystems in the Linux kernel, which means they are involved in the process of reviewing, discussing and merging patches contributed to those subsystems:

  • Maxime Ripard, as the Allwinner platform co-maintainer, merged 113 patches from other contributors
  • Boris Brezillon, as the MTD/NAND maintainer, merged 62 patches from other contributors
  • Alexandre Belloni, as the RTC maintainer and Atmel platform co-maintainer, merged 57 patches from other contributors
  • Grégory Clement, as the Marvell EBU co-maintainer, merged 47 patches from other contributors

Here is the commit by commit detail of our contributors to 4.13:

Linux 4.12, Bootlin contributions

Linus Torvalds has released the 4.12 Linux kernel a week ago, in what is the second biggest kernel release ever by number of commits. As usual, LWN had a very nice coverage of the major new features and improvements: first part, second part and third part.

LWN has also published statistics about the Linux 4.12 development cycles, showing:

  • Bootlin as the #14 contributing company by number of commits, with 221 commits, between Broadcom (230 commits) and NXP (212 commits)
  • Bootlin as the #14 contributing company number of changed lines, with 16636 lines changed, just two lines less than Mellanox
  • Bootlin engineer and MTD NAND maintainer Boris Brezillon as the #17 most active contributor by number of lines changed.

Our most important contributions to this kernel release have been:

  • On Atmel AT91 and SAMA5 platforms:
    • Alexandre Belloni has continued to upstream the support for the SAMA5D2 backup mode, which is a very deep suspend to RAM state, offering very nice power savings. Alexandre touched the core code in arch/arm/mach-at91 as well as pinctrl and irqchip drivers
    • Boris Brezillon has converted the Atmel PWM driver to the atomic API of the PWM subsystem, implemented suspend/resume and did a number of fixes in the Atmel display controller driver, and also removed the no longer used AT91 Parallel ATA driver.
    • Quentin Schulz improved the suspend/resume hooks in the atmel-spi driver to support the SAMA5D2 backup mode.
  • On Allwinner platforms:
    • Mylène Josserand has made a number of improvements to the sun8i-codec audio driver that she contributed a few releases ago.
    • Maxime Ripard added devfreq support to dynamically change the frequency of the GPU on the Allwinner A33 SoC.
    • Quentin Schulz added battery charging and ADC support to the X-Powers AXP20x and AXP22x PMICs, found on Allwinner platforms.
    • Quentin Schulz added a new IIO driver to support the ADCs found on numerous Allwinner SoCs.
    • Quentin Schulz added support for the Allwinner A33 built-in thermal sensor, and used it to implement thermal throttling on this platform.
  • On Marvell platforms:
    • Antoine Ténart contributed Device Tree changes to describe the cryptographic engines found in the Marvell Armada 7K and 8K SoCs. For now only the Device Tree description has been merged, the driver itself will arrive in Linux 4.13.
    • Grégory Clement has contributed a pinctrl and GPIO driver for the Marvell Armada 3720 SoC (Cortex-A53 based)
    • Grégory Clement has improved the Device Tree description of the Marvell Armada 3720 and Marvell Armada 7K/8K SoCs and corresponding evaluation boards: SDHCI and RTC are now enabled on Armada 7K/8K, USB2, USB3 and RTC are now enabled on Armada 3720.
    • Thomas Petazzoni made a significant number of changes to the mvpp2 network driver, finally adding support for the PPv2.2 version of this Ethernet controller. This allowed to enable network support on the Marvell Armada 7K/8K SoCs.
    • Thomas Petazzoni contributed a number of fixes to the mv_xor_v2 dmaengine driver, used for the XOR engines on the Marvell Armada 7K/8K SoCs.
    • Thomas Petazzoni cleaned-up the MSI support in the Marvell pci-mvebu and pcie-aardvark PCI host controller drivers, which allowed to remove a no-longer used MSI kernel API.
  • On the ST SPEAr600 platform:
    • Thomas Petazzoni added support for the ADC available on this platform, by adding its Device Tree description and fixing a clock driver bug
    • Thomas did a number of small improvements to the Device Tree description of the SoC and its evaluation board
    • Thomas cleaned up the fsmc_nand driver, which is used for the NAND controller driver on this platform, removing lots of unused code
  • In the MTD NAND subsystem:
    • Boris Brezillon implemented a mechanism to allow vendor-specific initialization and detection steps to be added, on a per-NAND chip basis. As part of this effort, he has split into multiple files the vendor-specific initialization sequences for Macronix, AMD/Spansion, Micron, Toshiba, Hynix and Samsung NANDs. This work will allow in the future to more easily exploit the vendor-specific features of different NAND chips.
  • Other contributions:
    • Maxime Ripard added a display panel driver for the ST7789V LCD controller

In addition, several Bootlin engineers are also maintainers of various kernel subsystems. During this release cycle, they reviewed and merged a number of patches from kernel contributors:

  • Maxime Ripard, as the Allwinner co-maintainer, merged 94 patches
  • Boris Brezillon, as the NAND maintainer and MTD co-maintainer, merged 64 patches
  • Alexandre Belloni, as the RTC maintainer and Atmel co-maintainer, merged 38 patches
  • Grégory Clement, as the Marvell EBU co-maintainer, merged 32 patches

The details of all our contributions for this release: