Linux 6.5 was released yesterday, with as usual over 10,000 commits from a large number of contributors. We recommend reading LWN.net articles on the merge window (part 1, part 2), but also the CNX Software page that focuses on embedded-related improvements.
Bootlin contributed 76 commits to this kernel release, putting us as the #26 contributing company. This time around, our main contributions have been:
The large stack of patches from Luca Ceresoli on the NVidia Tegra camera interface driver finally landed: they add support for the Tegra20 parallel camera interface to the existing driver, which required a lot of changes to the driver that was so far only support Tegra210 CSI. This work allows one of our customers, who was stuck on an old vendor NVidia kernel to an upstream Linux kernel.
Hervé Codina contributed a driver for the Renesas X9250potentiometer, in the IIO subsystem. This will be followed in Linux 6.6 by a glue driver that allows to expose an IIO device as an auxiliary device in the ALSA subsystem, allowing this potentiometer to be used in audio applications
Alexis Lothoré contributed support for the Marvell MV88E6361 Ethernet switch into the existing mv88e6xxx DSA driver
Maxime Chevallier contributed a new regmap-based MDIO driver, which required some changes in the regmap code. This allows the Altera TSE driver to use the existing Lynx PCS driver, and drop the custom Altera TSE PCS driver. Finally, the stmmac Ethernet driver is modified to be able to use the Lynx PCS driver as well. Quite an adventure to finally get proper PCS support with stmmac
Miquèl Raynal contributed improvments in the 802.15.4 stack, especially related to scanning support.
Miquèl Raynal contributed fixes to the sja1000 CAN driver (to avoid overrun stalls on Renesas processors), to the SPI subsystem (to avoid false timeouts for long transfers), to the DMA engine driver for Xilinx XDMA IP, and a few more.
Miquèl Raynal also continued his effort of improving the Device Tree bindings for MTD NAND controllers
Luca Ceresoli added sound card support to the MSC SM2-MB-EP1 carrier board, which runs a i.MX8MP SoM, and he also fixed the timings for one of the panels supported by the simple-panel driver
Here are the details of all our changes that went into Linux 6.5:
Linux 6.4 was released on June 25, just before the start of the Embedded Open Source Summit in Prague. As usual, lots of changes in Linux 6.4, and we recommend reading LWN coverage of the merge window (part 1, part 2). Sadly, the usual KernelNewbies page hasn’t received a lot of attention, contributions are probably welcome to revive this useful resource.
With 59 commits from Bootlin engineers, Bootlin is ranked as the #28 contributing company by number of commits for this 6.4 release, according to contribution statistics. Our main contributions have been:
Alexis Lothoré and Clément Léger contributed a few fixes to the Renesas RZ/N1 A5PSW Ethernet switch driver
Luca Ceresoli improved the fsl-ldb driver, used on NXP i.MX8MP and i.MX93 for the built-in DPI-to-LVDS encoder. Luca’s improvement allows to use LVDS channel 1 only, while the driver initially supported using either LVDS channel 0, or LVDS channel 0 and 1 combined.
Maxime Chevallier contributed an improvement to the regmap code, which allows upshifting register addresses before performing operations
Maxime Chevallier also contributed some small fixes to the phylink code related to previous work on QUSGMII support
Miquèl Raynal contributed the support for Real-While-Write in the MTD SPI-NOR subsystem. This allows to perform read operations while erase/program operations are on-going, which helps to reduce read latencies. This of course only works on SPI NOR chips that support this feature.
Miquèl Raynal contributed several improvements to the NVMEM subsystem. First, a brand new NVMEM driver capable of parsing the ONIE TLV information, as defined by the ONIE spec used on network equipment. Second, he contributed changes that allow NVMEM layout drivers to be compiled as kernel modules rather than being built-in
The Yocto Project has published its new release: 4.2, also known as “Mickledore”.
It features improved Rust support, BitBake engine improvements, support for Linux 6.1 (the latest Long Term Support kernel), new QEMU features, testing improvements and of course many other new features and package updates. See the release notes for all details.
At Bootlin, we contributed a total of 122 patches to this release, making Bootlin the 21st contributing company by number of commits according to statistics. Also Bootlin engineer Paul Kocialkowski appears in the top developers by changed lines in the Linux 6.2 statistics.
Linux 5.11 was released quite some time ago now, but it’s never too late to have a look at Bootlin contributions to this release. As usual, we recommend reading the LWN articles on the 5.11 merge window: part 1 and part2. Also of interest is the Kernelnewbies page for 5.11.
Here are the main highlights of our contributions:
Alexandre Belloni, as the maintainer of the RTC subsystem, continued making numerous improvements and fixes to RTC drivers
On the support for Microchip ARM platforms, Alexandre Belloni switched the PWM atmel-tcb driver to a new Device Tree binding and added SAMA5D2 support, he did some improvements to the IIO driver for the Microchip ADC, and continued to remove platform_data support from Microchip drivers as all platforms are now converted to the Device Tree.
Alexandre Belloni contributed a new Simple Audio Mux driver for the ALSA subsystem, which can be used to control simple audio multiplexers driven using GPIOs, that allows to select which of their input line is connected to the output line.
Grégory Clement added support for several new MIPS platforms from Microchip: Luton, Serval and Jaguar2. All those platforms include a MIPS core, a few peripherals and more importantly an Ethernet switch. For now the support only includes the base platform support, but we are working on the switchdev driver for the Ethernet switch.
Miquèl Raynal, maintainer of the NAND subsystem and co-maintainer of the MTD subsystem, contributed numerous changes to the ECC support in the MTD subsystem, making it more generic so that it can be used not just for parallel NAND flashes, but also SPI NAND flashes. For more details, see the talk from Miquèl Raynal on this topic.
In addition to those 95 patches that we authored and contributed, several Bootlin engineers being maintainers of different subsystems of the Linux kernel reviewed and merged patches from other contributors:
Miquèl Raynal, as the NAND maintainer and MTD co-maintainer, reviewed and merged 67 patches from other contributors
Alexandre Belloni, as the RTC, I3C and Microchip ARM/MIPS platforms maintainer, reviewed and merged 47 patches from other contributors
Grégory Clement, as the Marvell EBU platform co-maintainer, reviewed and merged 33 patches from other contributors
Here is the detailed list of our contributions to Linux 5.11:
Linux 5.6 was released last Sunday. As usual, LWN has the best coverage of the new features merged in this release: part 1 and part 2. Sadly, the corresponding KernelNewbies page has not yet been updated with the usual very interesting summary of the important changes.
Bootlin contributed a total of 95 patches to this release, which makes us the 27th contributing company by number of commits, according to the statistics. The main highlights of our contributions are:
Our work on supporting hardware-offloading of MACsec encryption/decryption in the networking subsystem and support for this offloading for some Microchip/Vitesse PHYs has been merged. See our previous blog post for more details about this work done by Bootlin engineer Antoine Ténart
As part of our work on the Rockchip PX30 system-on-chip, we contributed support for LVDS display on Rockchip PX30, and support for the Satoz SAT050AT40H12R2 panel. This work was done by Miquèl Raynal
Alexandre Belloni as the RTC maintainer did his usual number of cleanup and improvements to existing RTC drivers
We did a number of small contributions to the Microchip AT91/SAMA5 platform: support for the Smartkiz platform from Overkiz, phylink improvements in the macb driver, etc.
Paul Kocialkowski improved the Intel GMA 500 DRM driver to support page flip.
Paul Kocialkowski contributed support for the Xylon LogiCVC GPIO controller, which is a preliminary step to contributing the Xylon LogiCVC display controller support. See our blog post on this topic.
In addition to being contributors, a number of Bootlin engineers are also maintainers of various parts of the Linux kernel, and as such:
Alexandre Belloni, as the RTC subsystem maintainer and Microchip platforms co-maintainer, has reviewed and merged 55 patches from other contributors
Miquèl Raynal, as the MTD co-maintainer, has reviewed and merged 21 patches from other contributors
Grégory Clement, as the Marvell EBU platform co-maintainer, has reviewed and merged 12 patches from other contributors
This 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-i2saudio 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:
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 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:
At 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: