Linux 5.4 released, Bootlin contributions inside

LinuxThis time around, we’re quite late to the party, but Linux 5.4 was indeed released a number of weeks ago, and once again, Bootlin contributed a number of patches to this Linux kernel release. As usual, the most useful source of information to learn about the major features brought by Linux 5.4 are the LWN articles (part 1, part 2) and the KernelNewbies Wiki.

With a total of 143 patches contributed to this release, Bootlin is the 17th contributing company by number of commits acccording to the Linux Kernel Patch Statistic.

Here are the highlights of our contributions:

  • Antoine Ténart contributed support for IEEE 1588 Precision Time Protocol (PTP) to the Microsemi Ocelot Ethernet switch driver, which Bootlin developed and upstreamed in 2018 (see our blog post)
  • In the MTD subsystem, a number of contributions to the spi-nor support, written originally by Boris Brezillon, made their way upstream.
  • In the support of Microchip (formerly Atmel) platforms, Kamel Bouhara, who joined Bootlin in September 2019, sees his first kernel contribution merged as a Bootlin engineer: dropping useless support for platform_data from the Atmel PWM driver.
  • In the support of Allwinner platforms
    • Maxime Ripard contributed a brand new driver for the Allwinner A10 camera interface driver, a driver that we started at Bootlin for the CHIP platform back in the days, and that we finished more recently.
    • Maxime Ripard contributed a significant number of improvements to the sun4i-i2s audio interface driver, especially TDM support, which was developed as part of a customer project at Bootlin.
    • Maxime Ripard also contributed numerous enhancements to Allwinner platform Device Tree files, especially in the area of using YAML schemas.
  • In the support for Marvell platforms
    • Grégory Clement added cpufreq support to the Marvell Armada 7K/8K platform by extending some of its clock drivers.
    • Miquèl Raynal contributed improvements to the Marvell CP110 COMPHY driver, which is used to control SERDES lanes on the Marvell Armada 7K/8K platforms, and added the description of the SERDES lanes used by various IP blocks in those processors.
  • Alexandre Belloni, as the RTC subsystem maintainer, did a number of fixes and improvements in several RTC drivers (mainly pcf2123 and pcf8563)
  • For the LPC3250 platform, for which Bootlin delivered a modern BSP to a customer last year, Alexandre Belloni fixed an issue in the lpc_eth network driver, which was preventing the system from booting if the network had been initialized by the bootloader.

In addition to being contributors, some Bootlin engineers are also maintainers of various parts of the Linux kernel, and as such review and merge code from other contributors:

  • As the RTC subsystem maintainer and Microchip platform co-maintainer, Alexandre Belloni merged 47 patches from other contributors
  • As the MTD subsystem co-maintainer, Miquèl Raynal merged 33 patches from other contributors
  • As the Marvell platform co-maintainer, Grégory Clement merged 11 patches from other contributors

Here are the details of all our contributions to Linux 5.4:

Linux 5.3 released, Bootlin contributions inside

Penguin from Mylène Josserand
Drawing from Mylène Josserand, based on a picture from Samuel Blanc (https://commons.wikimedia.org/wiki/File:Manchot_royal_-_King_Penguin.jpg)
The 5.3 version of the Linux kernel was released recently. As usual, we recommend our readers to look at the LWN coverage for this release merge window: part 1 and part 2. Together with the KernelNewbies page, these articles give a very nice overview of the major features and improvements of this new release.

For this release, Bootlin is the 16th contributing company by number of commits, with 143 patches merged in the Linux kernel. Our significant contributions this time were:

  • Support for Allwinner processors
    • The support for H264 video decoding, from Maxime Ripard, was finally merged in the cedrus VPU driver that we have developed thanks to the funding of our Kickstarter campaign last year. The last missing piece is H265 video decoding, which we have submitted several times and we hope to get merged soon.
  • Support for Marvell platforms
    • Antoine Ténart contributed a number of bug fixes and updates to the inside-secure crypto driver, which is used for the cryptographic hardware accelerator found on Marvell Armada 3700 and Marvell Armada 7K/8K.
    • Maxime Chevallier contributed many improvements to the mvpp2 network driver, used on the Marvell Armada 375 and Armada 7K/8K systems. His patches improve the traffic classification offloading capabilities, a topic he will present in detail at the next Embedded Linux Conference Europe.
    • Miquèl Raynal added PHY support for the PCIe Armada 8K driver, and adjusted a few things in the Marvell Armada 7K/8K Device Tree files.
  • Support for Microchip MPU (formerly Atmel) platforms
    • Alexandre Belloni converted the remaining SoCs (SAM9x5, SAM9G45, SAM9RL and SAMA5D3) to the new slow clock controller bindings.
    • Antoine Ténart contributed a few small improvements to the macb driver, for the Cadence network controller used on Microchip platforms.
  • Maxime Ripard contributed numerous YAML Device Tree schemas, to help the effort of converting many Device Tree bindings to the new YAML format, which can be used to validate Device Trees against their bindings.
  • Maxime Ripard contributed numerous patches to the core DRM subsystem: a complete rewrite of the command line parser that parses the DRM-related options of the kernel command line, and support for new options. This was done as part of an effort to make sure the upstream Linux kernel can support all the possible options that the downstream RaspberryPi kernel+firmware combination provides to configure the display.
  • Paul Kocialkowski contributed a few improvements to the RaspberryPi vc4 display controller driver, related to buffer allocation.

Also, several of Bootlin engineers are also kernel maintainers, so they review and merge patches from other contributors:

  • Miquèl Raynal as the NAND subsystem maintainer and MTD subsystem co-maintainer, reviewed and merged 51 patches from other contributors
  • Maxime Ripard as the Allwinner platform co-maintainer, reviewed and merged 38 patches from other contributors
  • Alexandre Belloni as the RTC maintainer and Microchip platform co-maintainer, reviewed and merged 36 patches from other contributors
  • Grégory Clement as the Marvell EBU platform co-maintainer, reviewed and merged 9 patches from other contributors

Here is the details of all our contributions, patch by patch:

Linux 5.0 released, Bootlin contributions

Linux 5.0 was released two weeks ago by Linus Torvalds, and as it is now always the case, Bootlin has contributed a number of patches to this release. For an overview of the new features and improvements brought by Linux 5.0, we as usual recommend to read the LWN articles: merge window summary part 1, merge window summary part 2. The KernelNewbies.org page about this kernel release is also nicely documented.

In terms of contribution to Linux 5.0, according to the LWN statistics, Bootlin is the 12th contributing company by number of commits (261 commits), and 8th contributing company by number of changed lines. Bootlin engineer Maxime Ripard is 11th contributing developer by number of commits, and former Bootlin engineer Boris Brezillon is 12th contributing developer by number of commits, and 8th by number of changed lines. In this release, we are also happy to see numerous contributions from Paul Kocialkoswki who joined Bootlin in November 2018 after his internship working on the Linux kernel support for the Allwinner VPU.

Here are the main highlights of our contributions to Linux 5.0:

  • After 1.5 years of work, the I3C subsystem was finally merged and visible in drivers/i3c in your favorite kernel tree! We are proud to have pioneered the Linux kernel support for this new MIPI standard, which aims at providing an alternate solution to I2C and SPI, with interesting new features (higher speed, device discovery and enumeration, in-band interrupts, and more). See also our initial blog post about I3C, and our blog post about I3C being upstream.
  • In the RTC subsystem, Bootlin engineer and RTC kernel maintainer Alexandre Belloni reworked the way nvmem devices are handled, allowing for multiple nvmem devices to be registered for a single RTC as some have both battery-backed RAM and an on-chip EEPROM. devm_rtc_device_register() has been reimplemented to use the new registration path and is now deprecated. Its counterpart, devm_rtc_device_unregister() has been removed.
  • In the MTD subsystem
    • Boris Brezillon contributed a number of patches to the support for raw NAND mainly related to refactoring the subsystem. For example, some of the patches make the ->select_chip() of nand_chip a legacy hook, and removes its implementation from a number of drivers. All those patches do not bring any new feature per-se, but are part of a larger effort to clean up and modernize the MTD subsystem.
    • Boris Brezillon also contributed to the SPI NOR support a mechanism to fixup the information provided in the BFPT table of SPI NOR flashes. This is used to ensure that some Macronix SPI NOR flashes are properly recognized as supporting 4-byte opcodes.
  • Maxime Ripard contributed a number of improvements to the OV5640 camera sensor driver, especially to remove the hardcoded initialization sequence by a much more flexible initialization code, which allowed to support 60fps and more resolutions.
  • Maxime Ripard extended the PHY subsystem with two new functions, phy_configure() and phy_validate(), which allow to pass configuration details to PHY drivers. This was then used by Maxime to implement MIPI D-PHY drivers, which need a significant number of configuration parameters. See this commit and this commit for details. MIPI D-PHY are typically used in video display or capture HW pipelines.
  • As part of our work on RaspberryPi display support, Boris Brezillon contributed a number of fixs to the VC4 display controller driver.
  • For the support of Microchip MPU (Atmel) platforms, Alexandre Belloni migrated the AT91SAM9260, AT91SAM9261, AT91SAM9263, AT91SAM9RL, AT91SAM9x5, SAMA5D2 and SAMA5D4 platforms to the new clock Device Tree binding that he introduced in Linux 4.20.
  • For the support of Microchip UNG (formerly Microsemi) platforms, Alexandre Belloni added support for the Jaguar2 platform to the pinctrl driver already used for the Ocelot platform.
  • For the support of Allwinnner platforms:
    • Maxime Ripard did a huge amount of Device Tree cleanups and improvements, fixing DTC warnings, but generally making sure those Device Tree files are consistent.
    • Paul Kocialkowski implemented support for YUV planes in the Allwinner display controller driver. This allows to display a video decoded by the VPU directly into a display controller plane, and let the hardware compose it with other display planes, without CPU intervention.
    • Paul Kocialkowski enabled the VPU (for hardware-accelerated video decoding) on the Allwinner H5 and A64. This work was part of our crowdfunding campaign around the Allwinner VPU support.
  • For the support of Marvell platforms
    • Miquèl Raynal added support for suspend/resume to the SATA support on Armada 3720 (the SoC used for the popular EspressoBin platform), as part of a larger effort of bringing full suspend/resume support on Armada 3720
    • Miquèl Raynal implemented support for the thermal overheat interrupt on Armada 7K/8K.

Here is the detailed list of commits we contributed to Linux 5.0:

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: