Linux.conf.au, which takes place every year in January in Australia or New Zealand, is a major event of the Linux community. Free Electrons already participated to this event three years ago, and will participate again to this year’s edition, which will take place from January 16 to January 20 2017 in Hobart, Tasmania.
This time, Free Electrons CTO Thomas Petazzoni will give a talk titled A tour of the ARM architecture and its Linux support, in which he will share with LCA attendees what is the ARM architecture, how its Linux support is working, what the numerous variants of ARM processors and boards mean, what is the Device Tree, the ARM specific bootloaders, and more.
Last month, the entire Free Electrons engineering team attended the Embedded Linux Conference Europe in Berlin. The slides and videos of the talks have been posted, including the ones from the seven talks given by Free Electrons engineers:
Alexandre Belloni presented on ASoC: Supporting Audio on an Embedded Board, slides and video.
Boris Brezillon presented on Modernizing the NAND framework, the big picture, slides and video.
Boris Brezillon, together with Richard Weinberger from sigma star, presented on Running UBI/UBIFS on MLC NAND, slides and video.
Grégory Clement presented on Your newer ARM64 SoC Linux check list, slides and video.
Thomas Petazzoni presented on Anatomy of cross-compilation toolchains, slides and video.
Maxime Ripard presented on Supporting the camera interface on the C.H.I.P, slides and video.
Quentin Schulz and Antoine Ténart presented on Building a board farm: continuous integration and remote control, slides and video.
The 2016 edition of the Kernel Recipes conference will take place from September 28th to 30th in Paris. With talks from kernel developers Jonathan Corbet, Greg Kroah-Hartmann, Daniel Vetter, Laurent Pinchart, Tejun Heo, Steven Rosdedt, Kevin Hilman, Hans Verkuil and many others, the schedule looks definitely very appealing, and indeed the event is now full.
Thomas Petazzoni, Free Electrons CTO, will be attending this event. If you’re interested in discussing business or career opportunities with Free Electrons, this event will be a great place to meet together.
The next X.org Developer Conference will take place on September 21 to September 23 in Helsinki, Finland. This is a major event for Linux developers working in the graphics/display areas, not only at the X.org level, but also at the kernel level, in Mesa, and other related projects.
Free Electrons engineer Maxime Ripard will be attending this conference, with 80+ other engineers from Intel, Google, NVidia, Texas Instruments, AMD, RedHat, etc.
Maxime is the author of the DRM/KMS driver in the upstream Linux kernel for the Allwinner SoCs, which provides display support for numerous Allwinner platforms, especially Nextthing’s CHIP (with parallel LCD support, HDMI support, VGA support and composite video support). Maxime has also worked on making the 3D acceleration work on this platform with a mainline kernel, by adapting the Mali kernel driver. Most recently, Maxime has been involved in Video4Linux development, writing a driver for the camera interface of Allwinner SoCs, and supervising Florent Revest work on the Allwinner VPU that we published a few days ago.
This report gives a nice overview of the evolution of the Linux kernel since 3.18, especially from a contribution point of view: the rate of changes, who is contributing, are there new developers joining, etc.
Free Electrons is mentioned in several places in this report. First of all, even though Free Electrons is a consulting company, it is shown individually rather than part of the general “consultants” category. As the report explains:
The category “consultants” represents developers who contribute to the kernel as a work-for-hire effort from different companies. Some consultant companies, such as Free Electrons and Pengutronix, are shown individually as their contributions are a significant number.
Thanks to being mentioned separately from the “consultants” category, the report also shows that:
Free Electrons is the #15 contributing company over the 3.19 to 4.7 development period, in number of commits. Free Electrons contributed a total of 1453 commits, corresponding to 1.3% of the total commits
Free Electrons is ranked #13 in the list of companies by number of Signed-off-by from developers who are not the author of patches. This happens because 6 of our engineers are maintainers or co-maintainers from various areas in the kernel: they merge patches from contributors, sign-off on them, and send them to another maintainer (either arm-soc maintainers or directly Linus Torvalds, depending on the subsystem).
We’re glad to see Free Electrons mentioned in this report, which shows that we are a strong contributor to the official Linux kernel. Thanks to this contribution effort, we have tremendous experience with adding support for new hardware in the kernel, so contact us if you want your hardware supported in the official Linux kernel!
Over the last few years, and most recently with the support for the C.H.I.P platform, Free Electrons has been heavily involved in initiating and improving the support in the mainline Linux kernel for the Allwinner ARM processors. As of today, a large number of hardware features of the Allwinner processors, especially the older ones such as the A10 or the A13 used in the CHIP, are usable with the mainline Linux kernel, including complex functionality such as display support and 3D acceleration. However, one feature that was still lacking is proper support for the Video Processing Unit (VPU) that allows to accelerate in hardware the decoding and encoding of popular video formats.
The internship resulted in a new sunxi-cedrus driver, a Video4Linux memory-to-memory decoder kernel driver and a corresponding VA-API backend, which allows numerous userspace applications to use the decoding capabilities. Both projects have both been published on Github:
Currently, the combination of the kernel driver and VA-API backend supports MPEG2 and MPEG4 decoding only. There is for the moment no support for encoding, and no support for H264, though we believe support for both aspects can be added within the architecture of the existing driver and VA-API backend.
A first RFC patchset of the kernel driver has been sent to the linux-media mailing list, and a complete documentation providing installation information and architecture details has been written on the linux-sunxi’s wiki.
Here is a video of VLC playing a MPEG2 demo video on top of this stack on the Next Thing’s C.H.I.P:
The next Embedded Linux Conference Europe will take place from October 11 to October 13 in Berlin, Germany. As usual, the entire Free Electrons engineering team will participate, which means this time 10 participants from Free Electrons!
The schedule for the conference has been published recently, and a number of our talk proposals have been accepted, so we will present on the following topics:
Boris Brezillon, Free Electrons engineer and maintainer of the Linux kernel NAND subsystem, will be co-presenting with Richard Weinberger (from sigma star gmbh, and also co-maintainer of the UBI/UBIFS subsystems in the kernel) a talk on Running UBI/UBIFS on MLC NAND. Richard and Boris will present they have been doing over the last year to make UBI/UBIFS and generally the Linux MTD/NAND stack compatible with the constraints of MLC NANDs.
Boris Brezillon (again!) will also give a talk on Modernizing the NAND Framework: The Big Picture, in which he will describe his roadmap for the NAND subsystem, and gather input from the audience as to what needs to be improved in this subsystem.
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, Free Electrons 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).
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 Free Electrons 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, Free Electrons 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!
Boris Brezillon has contributed a core improvement to the PWM subsystem: a mechanism that allows to update the properties of a PWM in an atomic fashion. This is needed when a PWM has been initialized by the bootloader, and the kernel needs to take over without changing the properties of the PWM. See the main patch for more details. What prompted the creation of this patch series is a problem on Rockchip based Chromebook platforms where a PWM is used for a regulator, and the PWM properties need to be preserved across the bootloader to kernel transition. In addition to the changes of the core infrastructure, Boris contributed numerous patches to fix existing PWM users.
In the MTD subsystem, Boris Brezillon continued his cleanup efforts
Use the common Device Tree parsing code provided by nand_scan_ident() in more drivers, rather than driver-specific code.
Move drivers to expose their ECC/OOB layout information using the mtd_ooblayout_ops structure, and use the corresponding helper functions where appropriate. This change will allow a more flexible description of the ECC and OOB layout.
Document the Device Tree binding that should now be used for all NAND controllers / NAND chip, with a clear separation between the NAND controller and the NAND chip. See this commit for more details.
In the RTC subsystem, Mylène Josserand contributed numerous improvements to the rv3029 and m41t80 drivers, including the addition of the support for the RV3049 (the SPI variant of RV3029). See also our previous blog post on the support of Microcrystal’s RTCs/.
On the support of Atmel platforms
Boris Brezillon contributed a number of fixes and improvements to the atmel-hlcdc driver, the DRM/KMS driver for Atmel platforms
On the support of Allwinner platforms
Maxime Ripard contributed a brand new DRM/KMS driver to support the display controller found on several Allwinner platforms, with a specific focus on Allwinner A10. This new driver allows to have proper graphics support in the Nextthing Co. C.H.I.P platform, including composite output and RGB output for LCD panels. To this effect, in addition to the driver itself, numerous clock patches and Device Tree patches were made.
Boris Brezillon contributed a large number of improvements to the NAND controller driver used on Allwinner platforms, including performance improvements.
Quentin Schulz made his first kernel contribution by sending a patch fixing the error handling in a PHY USB driver used by Allwinner platforms.
On the support of Marvell platforms
Grégory Clement made some contributions to the mv_xor driver to make it 64-bits ready, as the same XOR engine is used on Armada 3700, a Cortex-A53 based SoC. Grégory then enabled the use of the XOR engines on this platform by updating the corresponding Device Tree.
Romain Perier did some minor updates related to the Marvell cryptographic engine support. Many more updates will be present in the upcoming 4.8, including significant performance improvements.
Thomas Petazzoni contributed some various fixes (cryptographic engine usage on some Armada 38x boards, HW I/O coherency related fixes).
Thomas also improved the support for Armada 7K and 8K, with the description of more hardware blocks, and updates to drivers.
Here are in details, the different contributions we made to this release: