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:

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:

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:

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:

Linux 4.7 statistics: Bootlin engineer #2 contributor

LWN.net has published yesterday an article containing statistics for the 4.7 development cycle. This article is available for LWN.net subscribers only during the coming week, and will then be available for everyone, free of charge.

It turns out that Boris Brezillon, Bootlin engineer, is the second most active contributor to the 4.7 kernel in number of commits! The top three contributors in number of commits are: H Hartley Sweeten (208 commits), Boris Brezillon (132 commits) and Al Viro (127 commits).

LWN.net 4.7 kernel statistics

In addition to being present in the most active developers by number of commits, Boris Brezillon is also in the #11 most active contributor in terms of changed lines. As we discussed in our previous blog post, most contributions from Boris were targeted at the PWM subsystem on one side (atomic update support) and the NAND subsystem on the other side.

Another Bootlin engineer shows up in the per-developer statistics: Maxime Ripard is the #17 most active contributor by lines changed. Indeed, Maxime contributed a brand new DRM/KMS driver for the Allwinner display controller.

As a company, Bootlin is ranked for the 4.7 kernel as the #12 most active company by number of commits, and #10 by number of changed lines. We are glad to continue being such a contributor to the Linux kernel development, as we have been for the last four years. If you want your hardware to be supported in the official Linux kernel, contact us!