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Commit 47eb1d84 authored by Florian Tobias Schandinat's avatar Florian Tobias Schandinat
Browse files

viafb: add documentation for proc interface 



This patch adds documentation for the new proc interface that allows
modification of the output device configuration. Should be stable and
useful enough now for daily use.

Signed-off-by: default avatarFlorian Tobias Schandinat <FlorianSchandinat@gmx.de>
Acked-by: default avatarJonathan Corbet <corbet@lwn.net>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Andrew Morton <akpm@linux-foundation.org>
parent a2aa9f9f

Documentation/fb/viafb.txt

+48 −0
Original line number Diff line number Diff line
@@ -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: