[PATCH] intelfb documentation
Add a small documentation of the driver parameters.
Signed-off-by: Sylvain Meyer <sylvain.meyer@worldonline.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/Documentation/fb/intelfb.txt b/Documentation/fb/intelfb.txt
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+Intel 830M/845G/852GM/855GM/865G/915G Framebuffer driver
+================================================================
+
+A. Introduction
+ This is a framebuffer driver for various Intel 810/815 compatible
+graphics devices. These would include:
+
+ Intel 830M
+ Intel 810E845G
+ Intel 852GM
+ Intel 855GM
+ Intel 865G
+ Intel 915G
+
+B. List of available options
+
+ a. "video=intelfb"
+ enables the intelfb driver
+
+ Recommendation: required
+
+ b. "mode=<xres>x<yres>[-<bpp>][@<refresh>]"
+ select mode
+
+ Recommendation: user preference
+ (default = 1024x768-32@70)
+
+ c. "vram=<value>"
+ select amount of system RAM in MB to allocate for the video memory
+ if not enough RAM was already allocated by the BIOS.
+
+ Recommendation: 1 - 4 MB.
+ (default = 4 MB)
+
+ d. "voffset=<value>"
+ select at what offset in MB of the logical memory to allocate the
+ framebuffer memory. The intent is to avoid the memory blocks
+ used by standard graphics applications (XFree86). Depending on your
+ usage, adjust the value up or down, (0 for maximum usage, 63/127 MB
+ for the least amount). Note, an arbitrary setting may conflict
+ with XFree86.
+
+ Recommendation: do not set
+ (default = 48 MB)
+
+ e. "accel"
+ enable text acceleration. This can be enabled/reenabled anytime
+ by using 'fbset -accel true/false'.
+
+ Recommendation: enable
+ (default = set)
+
+ f. "hwcursor"
+ enable cursor acceleration.
+
+ Recommendation: enable
+ (default = set)
+
+ g. "mtrr"
+ enable MTRR. This allows data transfers to the framebuffer memory
+ to occur in bursts which can significantly increase performance.
+ Not very helpful with the intel chips because of 'shared memory'.
+
+ Recommendation: set
+ (default = set)
+
+ h. "fixed"
+ disable mode switching.
+
+ Recommendation: do not set
+ (default = not set)
+
+ The binary parameters can be unset with a "no" prefix, example "noaccel".
+ The default parameter (not named) is the mode.
+
+C. Kernel booting
+
+Separate each option/option-pair by commas (,) and the option from its value
+with an equals sign (=) as in the following:
+
+video=i810fb:option1,option2=value2
+
+Sample Usage
+------------
+
+In /etc/lilo.conf, add the line:
+
+append="video=intelfb:800x600-32@75,accel,hwcursor,vram=8"
+
+This will initialize the framebuffer to 800x600 at 32bpp and 75Hz. The
+framebuffer will use 8 MB of System RAM. hw acceleration of text and cursor
+will be enabled.
+
+D. Module options
+
+ The module parameters are essentially similar to the kernel
+parameters. The main difference is that you need to include a Boolean value
+(1 for TRUE, and 0 for FALSE) for those options which don't need a value.
+
+Example, to enable MTRR, include "mtrr=1".
+
+Sample Usage
+------------
+
+Using the same setup as described above, load the module like this:
+
+ modprobe intelfb mode=800x600-32@75 vram=8 accel=1 hwcursor=1
+
+Or just add the following to /etc/modprobe.conf
+
+ options intelfb mode=800x600-32@75 vram=8 accel=1 hwcursor=1
+
+and just do a
+
+ modprobe intelfb
+
+
+E. Acknowledgment:
+
+ 1. Geert Uytterhoeven - his excellent howto and the virtual
+ framebuffer driver code made this possible.
+
+ 2. Jeff Hartmann for his agpgart code.
+
+ 3. David Dawes for his original kernel 2.4 code.
+
+ 4. The X developers. Insights were provided just by reading the
+ XFree86 source code.
+
+ 5. Antonino A. Daplas for his inspiring i810fb driver.
+
+ 6. Andrew Morton for his kernel patches maintenance.
+
+###########################
+Sylvain