Bronica Motor Drive SQ-i

I recently got a Bronica SQ-Ai medium format film camera which came with the Motor Drive SQ-i. Since I couldn’t find any documentation at all about it on the internet and had to figure it out for myself I figured I’d put what I figured out here. Hopefully this will help the next person trying […]

We show up

It’s really common for pitches to managements within companies about Linux kernel upstreaming to focus on cost savings to vendors from getting their code into the kernel, especially in the embedded space. These benefits are definitely real, especially for vendors trying to address the general market or extend the lifetime of their devices, but they […]

OpenTAC sprint

This weekend Toby Churchill kindly hosted a hacking weekend for OpenTAC – myself, Michael Grzeschik, Steve McIntyre and Andy Simpkins got together to bring up the remaining bits of the hardware on the current board revision and get some of the low level tooling like production flashing for the FTDI serial ports on the board up […]

Expedient ABIs

The biggest change we’ve seen in the Linux kernel for ARM over the past few years has been the transition to providing descriptions of the hardware in systems via device tree. This splits out the description of the devices in the system that can’t be automatically enumerated from the kernel into a separate binary instead […]

Performance problems

Just over a year ago I implemented an optimization to the SPI core code in Linux that avoids some needless context switches to a worker thread in the main data path that most clients use. This was really nice, it was simple to do but saved a bunch of work for most drivers using SPI and made things […]

Maintaining your email

One of the difficulties of being a kernel maintainer for a busy subsystem is that you will often end up getting a lot of mail that requires reading and handling which in turn requires sending a lot of mail out in reply. Some of that requires thought and careful consideration but a lot of it […]

Maximising the efficiency of chained regulators

Linux v4.4 will include a cool new feature contributed by Sascha Hauer of Pengutronix which propagates voltages set on a regulator to the regulators that supply it (taking into account the minimum headroom that the child regulator needs). The original reason for implementing it was to allow us to set voltages through simple unregulated power […]

Unconscious biases

Matthew Garrett’s recent very good response to Eric Raymond’s recent post opposing inclusiveness efforts in free software reminded me of something I’ve been noticing more and more often: a very substantial proportion of the female developers I encounter working on the kernel are from non-European cultures where I (and I expect most people from western cultures) lack […]

Flashing an AT91SAM9G20-EK from bare metal

Since I just had cause to do this and it was harder than it needed to be due to bitrot in the public documentation I could find I thought I’d write up how to get a modern bootloader onto older Atmel boards. These instructions are written for the AT91SAM9G20-EK though they should also apply to […]

Acer Aspire E11

Recently I was in Seoul in the middle of three weeks of travel and my laptop died on me.  Since I had some work that needed doing fairly urgently I took myself over to Yongsan Electronics Market and got myself a cheap replacement to tide myself over. What I ended up with was an Acer Aspire […]