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| -rw-r--r-- | Documentation/fb/viafb.txt | 48 |
1 files changed, 48 insertions, 0 deletions
diff --git a/Documentation/fb/viafb.txt b/Documentation/fb/viafb.txt index f3e046a6a98..1a2e8aa3fbb 100644 --- a/Documentation/fb/viafb.txt +++ b/Documentation/fb/viafb.txt @@ -197,6 +197,54 @@ Notes: example, # fbset -depth 16 + +[Configure viafb via /proc] +--------------------------- + The following files exist in /proc/viafb + + supported_output_devices + + This read-only file contains a full ',' seperated list containing all + output devices that could be available on your platform. It is likely + that not all of those have a connector on your hardware but it should + provide a good starting point to figure out which of those names match + a real connector. + Example: + # cat /proc/viafb/supported_output_devices + + iga1/output_devices + iga2/output_devices + + These two files are readable and writable. iga1 and iga2 are the two + independent units that produce the screen image. Those images can be + forwarded to one or more output devices. Reading those files is a way + to query which output devices are currently used by an iga. + Example: + # cat /proc/viafb/iga1/output_devices + If there are no output devices printed the output of this iga is lost. + This can happen for example if only one (the other) iga is used. + Writing to these files allows adjusting the output devices during + runtime. One can add new devices, remove existing ones or switch + between igas. Essentially you can write a ',' seperated list of device + names (or a single one) in the same format as the output to those + files. You can add a '+' or '-' as a prefix allowing simple addition + and removal of devices. So a prefix '+' adds the devices from your list + to the already existing ones, '-' removes the listed devices from the + existing ones and if no prefix is given it replaces all existing ones + with the listed ones. If you remove devices they are expected to turn + off. If you add devices that are already part of the other iga they are + removed there and added to the new one. + Examples: + Add CRT as output device to iga1 + # echo +CRT > /proc/viafb/iga1/output_devices + + Remove (turn off) DVP1 and LVDS1 as output devices of iga2 + # echo -DVP1,LVDS1 > /proc/viafb/iga2/output_devices + + Replace all iga1 output devices by CRT + # echo CRT > /proc/viafb/iga1/output_devices + + [Bootup with viafb]: -------------------- Add the following line to your grub.conf: |