diff options
Diffstat (limited to 'Documentation/fb/udlfb.txt')
| -rw-r--r-- | Documentation/fb/udlfb.txt | 39 |
1 files changed, 27 insertions, 12 deletions
diff --git a/Documentation/fb/udlfb.txt b/Documentation/fb/udlfb.txt index 7fdde2a02a27..57d2f2908b12 100644 --- a/Documentation/fb/udlfb.txt +++ b/Documentation/fb/udlfb.txt @@ -87,23 +87,38 @@ Special configuration for udlfb is usually unnecessary. There are a few options, however. From the command line, pass options to modprobe -modprobe udlfb defio=1 console=1 +modprobe udlfb fb_defio=0 console=1 shadow=1 -Or for permanent option, create file like /etc/modprobe.d/options with text -options udlfb defio=1 console=1 +Or modify options on the fly at /sys/module/udlfb/parameters directory via +sudo nano fb_defio +change the parameter in place, and save the file. -Accepted options: +Unplug/replug USB device to apply with new settings + +Or for permanent option, create file like /etc/modprobe.d/udlfb.conf with text +options udlfb fb_defio=0 console=1 shadow=1 + +Accepted boolean options: fb_defio Make use of the fb_defio (CONFIG_FB_DEFERRED_IO) kernel module to track changed areas of the framebuffer by page faults. - Standard fbdev applications that use mmap but that do not - report damage, may be able to work with this enabled. - Disabled by default because of overhead and other issues. - -console Allow fbcon to attach to udlfb provided framebuffers. This - is disabled by default because fbcon will aggressively consume - the first framebuffer it finds, which isn't usually what the - user wants in the case of USB displays. + Standard fbdev applications that use mmap but that do not + report damage, should be able to work with this enabled. + Disable when running with X server that supports reporting + changed regions via ioctl, as this method is simpler, + more stable, and higher performance. + default: fb_defio=1 + +console Allow fbcon to attach to udlfb provided framebuffers. + Can be disabled if fbcon and other clients + (e.g. X with --shared-vt) are in conflict. + default: console=1 + +shadow Allocate a 2nd framebuffer to shadow what's currently across + the USB bus in device memory. If any pixels are unchanged, + do not transmit. Spends host memory to save USB transfers. + Enabled by default. Only disable on very low memory systems. + default: shadow=1 Sysfs Attributes ================ |