Linux 5.2 released, Bootlin contributions inside

Penguin from Mylène Josserand
Drawing from Mylène Josserand, based on a picture from Samuel Blanc (
Linux 5.2 was released not long ago, and as usual it is time to have a look at the contributions that Bootlin engineers did to this kernel release. But before that, if you’re interested in having an overview of the major new features of this kernel, we recommend reading LWN articles covering the 5.2 merge window period: part 1 and part 2. KernelNewbies also has an interesting page about Linux 5.2.

With 350 patches contributed by Bootlin engineers, Bootlin is the 10th contributing company by number of commits for the Linux 5.2 release. With 186 commits, Alexandre Belloni is the second contributor to this release by number of commits (see also the detailed statistics from

Here are the highlights of our contributions:

  • In the RTC subsystem
    • Alexandre Belloni (maintainer of the subsystem) was very active in fixing a large number of drivers to use more modern APIs/mechanisms of the RTC core: use of rtc_time64_to_tm()/rtc_tm_to_time64(), use of devm_rtc_allocate_device(), etc.
    • Alexandre Belloni improved the pcf85063 driver with new features: alarm support, Micro Crystal RV8263 support, nvram support, offset correction support, RTC_VL_READ/RTC_VL_CLR support
  • In the support for the Microchip MPU (formerly Atmel) platforms
    • Alexandre Belloni continued the rework of the AT91/SAMA5 clock drivers, adding support for the new sam9x60 SoC using the new clock driver logic and DT binding
    • Alexandre Belloni dropped support for the AVR32 architecture and platform_data probing in the atmel_lcdfb driver, since AVR32 has been removed from the kernel
    • Alexandre Belloni also worked on the clocksource support on Microchip platforms. First, he made the TCB clocksource driver independent from the common atmel_tclib driver, so that TCB timers can be registered early enough in the kernel boot process. Then, he introduced the possibility of selecting the clocksource between TCB and PIT on Microchip platforms that support both. And finally modified the atmel_tclib driver to no longer use TCB timers that are used by the TCB clocksource driver registered early at boot time. The main motivation for this work is that some of the latest Microchip SoCs only have TCB timers available, and no longer the PIT, so we really needed to be able to use TCB as clocksource.
  • In the support for Marvell platforms
    • Maxime Chevallier contributed a number of patches to the mvpp2 Ethernet controller driver, adding support for classification offloading. This allows the HW to directly classify received network packets according to various details of their header, and steer them to the appropriate RX queue.
    • Maxime Chevallier contributed 2500Base-X support for the mvneta Ethernet controller driver.
  • In the support for Allwinner platforms
    • Miquèl Raynal contributed DMA support in the sunxi NAND controller driver, for the A23 and A33 SoC, significantly improving NAND read/write performance.
    • Paul Kocialkowski contributed a new Device Tree to support the RerVision H3-DVK platform
    • Quentin Schulz added support for the AXP813 PMIC in the axp20x_usb_power driver, and made a few other related contributions
    • Maxime Ripard made several improvements in the Allwinner DRM sun4i driver, especially improving the support for MIPI DSI display panels: the driver will now support a wider range of panels connected over DSI.
    • Maxime Ripard contributed many new DT bindings written in YAML, and as part of this, fixed a number of issues in the Allwinner platform Device Trees.
  • In the support for the NXP LPC3250 platform
    • Alexandre Belloni fixed a number of issues in the lpc32xx USB gadget driver, and added support for using the stotg04 USB PHY
    • Grégory Clement made a few cleanups in the lpc32xx IIO ADC driver, and added support for providing a scaled value and not just the raw ADC value
  • In the support for RaspberryPi platforms
    • Paul Kocialkowski finalized some work initially started by Boris Brezillon, to be able to track and detect the memory bandwidth used by the configuration of the RaspberryPi display engine, and prevent from making configurations that exhaust the available memory bandwidth.
  • In the MTD subsystem
    • Miquèl Raynal has become one of the co-maintainers of the MTD subsystem. He was already a co-maintainer for the NAND subsystem, which sits “under” MTD in the maintainer tree.
  • In the GPIO subsystem
    • Alexandre Belloni added support for the PCA6416 I2C GPIO expander to the existing gpio-pca953x driver
  • In the networking subsystem
    • Antoine Ténart implemented suspend/resume support in the Marvell 10G PHY driver, implemented a work-around for a HW errata in the Micrel PHY driver, and fixed an initialization issue in the same Micrel PHY driver.
  • In the IIO subsystem
    • Grégory Clement contributed a brand new IIO driver for the TI ADS8344 ADC chip, connected over SPI
  • Other topics
    • Maxime Ripard contributed some changes to the Device Tree address translation logic. Indeed, the Allwinner display engine does its DMA operations through a bus different from the bus used by the CPU core to access the display engine registers, and due to this, it sees the RAM at a different address. Thanks to the changes from Maxime, the DMA address translation now follows the interconnects property if it exists, instead of assuming the parent Device Tree node should be used.

Also, several of the engineers working at Bootlin are maintainers of specific parts of the kernel, and as part of their maintainer work, they review and merge patches from other contributors, before sending them to another upstream maintainer.

  • Miquèl Raynal, as one of the maintainers of the NAND and MTD subsystems, reviewed and merged 83 patches from other contributors
  • Maxime Ripard, one of two co-maintainers of the support for Allwinner processors, reviewed and merged 68 patches from other contributors
  • Alexandre Belloni, as the maintainer of the RTC subsystem and co-maintainer of the support for Microchip MPU processors, reviewed and merged 38 patches from other contributors
  • Grégory Clement, as the co-maintainer of the support for Marvell EBU processors, reviewed and merged 10 patches from other contributors

And as usual, the details of all contributions, commit by commit:

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...

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