CM-iGT: Linux: Mint

Overview

• Linux on CM-iGT is Linux Mint 17 LTS with full-featured MATE desktop environment
• All necessary drivers and tools are already installed
• Networking, sound, video acceleration, 2D and 3D graphics and other features work out of the box

Features such as TPM and CAN are unsupported in this release

ATI Catalyst video driver

The proprietary ATI Catalyst video driver for Radeon HD 6250 GPU provides the following features:

• GPU accelerated video decoding XvBA (X-video Bitstream Acceleration)
• Dual-head support
• Up to 1920x1200 at 60 Hz resolution
• 1080p playback with media players that support XvBA (XBMC and VLC)

The ATI Catalyst driver, VLC, XBMC and other required utilities were installed using the following command:

$ sudo apt-get install fglrx-updates xvba-va-driver vainfo xbmc vlc

GPIO

GPIO interface on SB-iGT consists of 15 I/Os provided by AMD FCH (Fusion Controller Hub)

• All the I/Os have interrupt functions and can support asynchronous interrupts
• The responsible kernel module is fch_gpio
• The kernel modules uses the following pin naming convention:

GPIO pin naming convention on SB-iGT

GPIO name	HW source	Name on SB-iGT board	Pin on SB-iGT board	Notes
GPIO11	FCH	FCH_GPIO11	P15-4
GPIO14	FCH	FCH_GPIO14	P15-18
GPIO201	FCH	FCH_GPIO201_S5	P15-29	Active in S0 and S5 power states
GPIO202	FCH	FCH_GPIO202_S5	P15-31	Active in S0 and S5 power states
GPIO204	FCH	FCH_GPIO204_S5	P15-33	Active in S0 and S5 power states
GPIO205	FCH	FCH_GPIO205_S5	P15-35	Active in S0 and S5 power states
GPIO54	FCH	FN2PW M_GPIO54	P14-11
GPIO56	FCH	FNTH_GPIO56	P14-15
GPIO57	FCH	FNTH1_GPIO57	P14-17
GPIO58	FCH	FNTH2_GPIO58	P14-21
GPIO170	FCH	AZ_SI3_GPIO170	P14-28
GPIO172	FCH	TIN1_GPIO172	P14-5
GPIO173	FCH	TIN1_GPIO173	P14-7
GPIO197	FCH	TMR0_GPIO197	P14-4
GPIO198	FCH	TMR0_GPIO198	P14-6

• The GPIO sysfs interface allows users to manipulate any GPIO from userspace dynamically.
• A basic example of GPIO usage (as root user):

$ modprobe fch_gpio
$ echo 11 > /sys/class/gpio/export
$ echo out > /sys/class/gpio/gpio11/direction
$ echo 1 > /sys/class/gpio/gpio11/value
## at this point voltage measuring on P15,4 (FCH_GPIO11) should give 3.3V
$ echo 0 > /sys/class/gpio/gpio11/value
## at this point voltage measuring on P15,4 (FCH_GPIO11) should give 0.0V
$ echo 11 > /sys/class/gpio/unexport

• The GPIO framework and GPIO sysfs interface are documented in Linux Kernel Documentation :: GPIO

Serial communication

• COM1: Full modem control circuitry, baud rate from 30 bps to 250 Kbps, device node /dev/ttyS0
• COM2: 2-wire, baud rate from 50 bps to 460 Kbps, device node /dev/ttyS1
• Autologin from the serial console COM2 as root is enabled:

/etc/init/ttyS1.conf:

start on stopped rc RUNLEVEL=[2345]
stop on runlevel [!2345]

respawn
exec /sbin/getty -l /usr/bin/autologin -n -8 115200 ttyS1

/usr/bin/autologin (with chmod +x):

#!/bin/sh
exec /bin/login -f root

• Connect your host PC to the COM2 on SB-iGT via the serial cable
• Start terminal emulation on your host PC. Set baud rate to 115200 bps, 8 bit per frame, 1 stop bit, no parity, no flow control
• As a result, you automatically login on CM-iGT as root

Watchdog

The AMD FCH supports a user configurable watchdog.

Once the watchdog is enabled the system restarts once the timeout period elapses, so in order to prevent it the user needs to either feed the watchdog or to disable it.

• By default the timeout value is 60 sec and the watchdog deamon feeds the watchdog every 10 sec
• The responsible kernel module is sp5100_tco
• You can overwrite the default settings in /etc/watchdog.conf and /etc/default/watchdog
• Watchdog is already installed and configured on the Linux image provided by CompuLab
• As example you can simulate kernel panic (as root user):

$ echo c > /proc/sysrq-trigger

• As a result, the watchdog is not fed and the system will reboot after 60 sec

CAN bus

• currently unsupported

TPM

• currently unsupported

See also

• Getting started with Linux on CM-iGT
• Linux Kernel for CM-iGT