Sebastian Reichel

Collabora & Linux Kernel 4.13

Linux kernel v4.13 was released and - like in the v4.12 release - 12 Collabora developers contributed a total of 72 patches. In addition Collabora developers provided 25 Reviewed-by tags and 10 Tested-by tags. Furthermore 83 patches received a Signed-off-by tag from Collabora peoples. Again, general information about the merge window is available by in form of the following articles: part 1 and part 2. Now here is a look at the specific changes made by Collaborans. Read more →

Motorola Droid 4 - August Update

It has been some time since my last post about the Droid 4. 4.13 will most likely be released next week, so let’s have a look at newly added features related to the Droid 4: crypto acceleration for AES and 3DES support for ISL29030 (proximity and ambient light sensor) USB phy support battery monitoring support bluetooth Unfortunately the list for 4.14 will be a lot shorter (or even empty), since most other submissions are still in review (or need work). Read more →


This year the annual European Hacker camping event took place in the Netherlands. I have been there together with 12 fellow people from my hackerspace and we had fun again. This time we came better prepared than at the last German CCC camp (2015), which was a good thing since we had a lot more rain. We had a nice time with a wired dual GBit ethernet internet connection to our village, decent power supply, a big tent with benches and tables for day activities, a few fridges and lots of food. Read more →

Device Tree Overlays

In my local hackerspace I maintain a Raspberry Pi based system with some hardware extensions (mainly I2C devices). It’s running with Debian’s kernel and a patched device tree for the additional hardware components. This is the ideal candidate for DT overlays, so that I can use the DT blob provided by Debian and automatically apply the custom changes in top. With DT overlays from configfs still not being available I thought about giving the U-Boot “fdt apply” command added by Maxime Ripard from Free Electrons a chance. Read more →

Motorola Droid 4 - Update

The 4.12 merge window will most likely close on Sunday, so its a good time to check the Droid 4 status matrix. This merge window lots of changes were queued: New drivers: real time clock (RTC), power button, analogue digital converter (ADC), battery charger, LEDs (RGB, capslock status, android buttons) DTS additions: LCD (no driver yet), HDMI, Keyboard/LCD backlight (no driver yet), Touchscreen, Temperature sensor, Accelerometer, Compass, Regulators, RTC, Power button, ADC, USB PHY (no driver yet), Battery charger, LEDs, Keyboard, Poweroff, USB configuration for modems Read more →

I2C kernel driver testing using virtme

The last few days I worked on the MCP23017 kernel driver and wondered about a good method to test my changes in a comfortable way. Fortunately I built myself an i2c-tiny-usb adapter some time ago, which is supported by mainline Linux. Thus any system with USB host support could be used for testing the above chip. My minimal test-setup can be seen in the image below. Basically I supplied 5V, Ground, SCL & SDA from the adapter to MCP23017, connected the low-active reset pin to 5V and the address-selection pins to Ground. Read more →

Hiking West Highland Way

I recently walked the West Highland Way, which is already described extensively on lots of webpages. In contrast to most suggestions I walked in the first April week to avoid scotland’s midges. Also I did not travel from hotel to hotel or even campsite to campsite, but with a backpack providing all resources for approx. 10 days and did wild camping near the trail.

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I2C on RPi

Back in January I wrote about the Raspberry Pi’s I2C module having problems with a specific I2C feature: clock stretching. The planned workaround was using a NXP SC18IS600, since Cypress CP2120 only comes in a QFN package. I received the chips some time ago and use it since a month for our hackerspace’s access control system. Unfortunately the Linux kernel only came with a driver for NXP SC18IS602, which does the the other direction (I2C -> SPI). Read more →

Motorola Droid 4 - WL1285 and GPS

Today I had another look at GPS for Droid 4. In theory it has 3 different chips, that have GPS receivers: WL1285C, MDM6600, WG3LTE. The Cyanogenmod changelog for the Droid 4 contains a hint, that WL1285C’s GPS module is the one actually used: Don't hold st_wakelock until BT/GPS is used for the first time Also the stock kernel contains a driver for GPS from WiLink. WiLink based chips come with either SPI or SDIO connection for WLAN and a shared UART for Bluetooth (BT), FM radio, GPS and NFC. Read more →

Motorola Droid 4 - Update

Some time has gone by since my last post, so lets have a look what changed for Droid 4: I prepared a CPCAP LED driver I published updated patches for the N950 display (also used for D4) Milo Kim published TI LMU backlight driver supporting D4’s LM3532 Tony published a CPCAP ADC driver Tony published a simple CPCAP battery charer driver Tony published CPCAP usb phy Tony published Motorola MDM6600 patch for qmi_wwan Tony published lots of droid 4 DTS patches adding Touchscreen LCD backlight GPIO poweroff Temperature sensor HDMI support (incl. Read more →