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linux-next/Documentation/fb/viafb.txt
Florian Tobias Schandinat 47eb1d8417 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: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Acked-by: Jonathan Corbet <corbet@lwn.net>
Cc: Joseph Chan <JosephChan@via.com.tw>
Cc: Andrew Morton <akpm@linux-foundation.org>
2010-09-24 02:15:27 +00:00

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VIA Integration Graphic Chip Console Framebuffer Driver
[Platform]
-----------------------
The console framebuffer driver is for graphics chips of
VIA UniChrome Family(CLE266, PM800 / CN400 / CN300,
P4M800CE / P4M800Pro / CN700 / VN800,
CX700 / VX700, K8M890, P4M890,
CN896 / P4M900, VX800, VX855)
[Driver features]
------------------------
Device: CRT, LCD, DVI
Support viafb_mode:
CRT:
640x480(60, 75, 85, 100, 120 Hz), 720x480(60 Hz),
720x576(60 Hz), 800x600(60, 75, 85, 100, 120 Hz),
848x480(60 Hz), 856x480(60 Hz), 1024x512(60 Hz),
1024x768(60, 75, 85, 100 Hz), 1152x864(75 Hz),
1280x768(60 Hz), 1280x960(60 Hz), 1280x1024(60, 75, 85 Hz),
1440x1050(60 Hz), 1600x1200(60, 75 Hz), 1280x720(60 Hz),
1920x1080(60 Hz), 1400x1050(60 Hz), 800x480(60 Hz)
color depth: 8 bpp, 16 bpp, 32 bpp supports.
Support 2D hardware accelerator.
[Using the viafb module]
-- -- --------------------
Start viafb with default settings:
#modprobe viafb
Start viafb with with user options:
#modprobe viafb viafb_mode=800x600 viafb_bpp=16 viafb_refresh=60
viafb_active_dev=CRT+DVI viafb_dvi_port=DVP1
viafb_mode1=1024x768 viafb_bpp=16 viafb_refresh1=60
viafb_SAMM_ON=1
viafb_mode:
640x480 (default)
720x480
800x600
1024x768
......
viafb_bpp:
8, 16, 32 (default:32)
viafb_refresh:
60, 75, 85, 100, 120 (default:60)
viafb_lcd_dsp_method:
0 : expansion (default)
1 : centering
viafb_lcd_mode:
0 : LCD panel with LSB data format input (default)
1 : LCD panel with MSB data format input
viafb_lcd_panel_id:
0 : Resolution: 640x480, Channel: single, Dithering: Enable
1 : Resolution: 800x600, Channel: single, Dithering: Enable
2 : Resolution: 1024x768, Channel: single, Dithering: Enable (default)
3 : Resolution: 1280x768, Channel: single, Dithering: Enable
4 : Resolution: 1280x1024, Channel: dual, Dithering: Enable
5 : Resolution: 1400x1050, Channel: dual, Dithering: Enable
6 : Resolution: 1600x1200, Channel: dual, Dithering: Enable
8 : Resolution: 800x480, Channel: single, Dithering: Enable
9 : Resolution: 1024x768, Channel: dual, Dithering: Enable
10: Resolution: 1024x768, Channel: single, Dithering: Disable
11: Resolution: 1024x768, Channel: dual, Dithering: Disable
12: Resolution: 1280x768, Channel: single, Dithering: Disable
13: Resolution: 1280x1024, Channel: dual, Dithering: Disable
14: Resolution: 1400x1050, Channel: dual, Dithering: Disable
15: Resolution: 1600x1200, Channel: dual, Dithering: Disable
16: Resolution: 1366x768, Channel: single, Dithering: Disable
17: Resolution: 1024x600, Channel: single, Dithering: Enable
18: Resolution: 1280x768, Channel: dual, Dithering: Enable
19: Resolution: 1280x800, Channel: single, Dithering: Enable
viafb_accel:
0 : No 2D Hardware Acceleration
1 : 2D Hardware Acceleration (default)
viafb_SAMM_ON:
0 : viafb_SAMM_ON disable (default)
1 : viafb_SAMM_ON enable
viafb_mode1: (secondary display device)
640x480 (default)
720x480
800x600
1024x768
... ...
viafb_bpp1: (secondary display device)
8, 16, 32 (default:32)
viafb_refresh1: (secondary display device)
60, 75, 85, 100, 120 (default:60)
viafb_active_dev:
This option is used to specify active devices.(CRT, DVI, CRT+LCD...)
DVI stands for DVI or HDMI, E.g., If you want to enable HDMI,
set viafb_active_dev=DVI. In SAMM case, the previous of
viafb_active_dev is primary device, and the following is
secondary device.
For example:
To enable one device, such as DVI only, we can use:
modprobe viafb viafb_active_dev=DVI
To enable two devices, such as CRT+DVI:
modprobe viafb viafb_active_dev=CRT+DVI;
For DuoView case, we can use:
modprobe viafb viafb_active_dev=CRT+DVI
OR
modprobe viafb viafb_active_dev=DVI+CRT...
For SAMM case:
If CRT is primary and DVI is secondary, we should use:
modprobe viafb viafb_active_dev=CRT+DVI viafb_SAMM_ON=1...
If DVI is primary and CRT is secondary, we should use:
modprobe viafb viafb_active_dev=DVI+CRT viafb_SAMM_ON=1...
viafb_display_hardware_layout:
This option is used to specify display hardware layout for CX700 chip.
1 : LCD only
2 : DVI only
3 : LCD+DVI (default)
4 : LCD1+LCD2 (internal + internal)
16: LCD1+ExternalLCD2 (internal + external)
viafb_second_size:
This option is used to set second device memory size(MB) in SAMM case.
The minimal size is 16.
viafb_platform_epia_dvi:
This option is used to enable DVI on EPIA - M
0 : No DVI on EPIA - M (default)
1 : DVI on EPIA - M
viafb_bus_width:
When using 24 - Bit Bus Width Digital Interface,
this option should be set.
12: 12-Bit LVDS or 12-Bit TMDS (default)
24: 24-Bit LVDS or 24-Bit TMDS
viafb_device_lcd_dualedge:
When using Dual Edge Panel, this option should be set.
0 : No Dual Edge Panel (default)
1 : Dual Edge Panel
viafb_lcd_port:
This option is used to specify LCD output port,
available values are "DVP0" "DVP1" "DFP_HIGHLOW" "DFP_HIGH" "DFP_LOW".
for external LCD + external DVI on CX700(External LCD is on DVP0),
we should use:
modprobe viafb viafb_lcd_port=DVP0...
Notes:
1. CRT may not display properly for DuoView CRT & DVI display at
the "640x480" PAL mode with DVI overscan enabled.
2. SAMM stands for single adapter multi monitors. It is different from
multi-head since SAMM support multi monitor at driver layers, thus fbcon
layer doesn't even know about it; SAMM's second screen doesn't have a
device node file, thus a user mode application can't access it directly.
When SAMM is enabled, viafb_mode and viafb_mode1, viafb_bpp and
viafb_bpp1, viafb_refresh and viafb_refresh1 can be different.
3. When console is depending on viafbinfo1, dynamically change resolution
and bpp, need to call VIAFB specified ioctl interface VIAFB_SET_DEVICE
instead of calling common ioctl function FBIOPUT_VSCREENINFO since
viafb doesn't support multi-head well, or it will cause screen crush.
[Configure viafb with "fbset" tool]
-----------------------------------
"fbset" is an inbox utility of Linux.
1. Inquire current viafb information, type,
# fbset -i
2. Set various resolutions and viafb_refresh rates,
# fbset <resolution-vertical_sync>
example,
# fbset "1024x768-75"
or
# fbset -g 1024 768 1024 768 32
Check the file "/etc/fb.modes" to find display modes available.
3. Set the color depth,
# fbset -depth <value>
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:
append = "video=viafb:viafb_mode=1024x768,viafb_bpp=32,viafb_refresh=85"
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