Linux and Android, switching between different display types
Posted: Sat Sep 01, 2012 2:21 am
Many of us may face to switch between different LCD displays when we are in development or integration. Here is a purposal for various display switching, within a unique pre-built kernel image.
For example, in TI-Android-ICS-4.0.3-DevKit-3.0.1, default bootargs is something like:
console=ttyO0,115200n8 androidboot.console=ttyO0 mem=256M root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait init=/init ip=off
With this default bootargs, linux kernel will boot up to default display settings for Beadaframe 7" LCD screen. For an alternative to a 4.3" LCD screen, we can change the default bootargs and add those 2 new parameters:
console=ttyO0,115200n8 androidboot.console=ttyO0 mem=256M lcd=h43i bl=21,100,100,1000000 root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait init=/init ip=off
Parameters Desription:
lcd=h43i /* This for h43i 4.3" 480x272 LCD display module. */
bl=21,100,100,1000000 /* h43i LCD display requires a distinct pwm frequency for backlight control than Beadaframe 7" LCD module. So we set it here. */
lcd=t35 /* This for t35 3.5" 240x320 LCD display module. */
bl=21,100,100,1000000 /* t35 LCD display requires a distinct pwm frequency for backlight control than Beadaframe 7" LCD module. So we set it here. */
lcd=a56 /* This for a56 5.6" 640x480 LCD display module. */
For example, in TI-Android-ICS-4.0.3-DevKit-3.0.1, default bootargs is something like:
console=ttyO0,115200n8 androidboot.console=ttyO0 mem=256M root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait init=/init ip=off
With this default bootargs, linux kernel will boot up to default display settings for Beadaframe 7" LCD screen. For an alternative to a 4.3" LCD screen, we can change the default bootargs and add those 2 new parameters:
console=ttyO0,115200n8 androidboot.console=ttyO0 mem=256M lcd=h43i bl=21,100,100,1000000 root=/dev/mmcblk0p2 rw rootfstype=ext4 rootwait init=/init ip=off
Parameters Desription:
lcd=h43i /* This for h43i 4.3" 480x272 LCD display module. */
bl=21,100,100,1000000 /* h43i LCD display requires a distinct pwm frequency for backlight control than Beadaframe 7" LCD module. So we set it here. */
lcd=t35 /* This for t35 3.5" 240x320 LCD display module. */
bl=21,100,100,1000000 /* t35 LCD display requires a distinct pwm frequency for backlight control than Beadaframe 7" LCD module. So we set it here. */
lcd=a56 /* This for a56 5.6" 640x480 LCD display module. */