xref: /openbmc/linux/Documentation/fb/intel810.rst (revision 2cf1c348)
1================================
2Intel 810/815 Framebuffer driver
3================================
4
5Tony Daplas <adaplas@pol.net>
6
7http://i810fb.sourceforge.net
8
9March 17, 2002
10
11First Released: July 2001
12Last Update:    September 12, 2005
13
14A. Introduction
15===============
16
17	This is a framebuffer driver for various Intel 810/815 compatible
18	graphics devices.  These include:
19
20	- Intel 810
21	- Intel 810E
22	- Intel 810-DC100
23	- Intel 815 Internal graphics only, 100Mhz FSB
24	- Intel 815 Internal graphics only
25	- Intel 815 Internal graphics and AGP
26
27B.  Features
28============
29
30	- Choice of using Discrete Video Timings, VESA Generalized Timing
31	  Formula, or a framebuffer specific database to set the video mode
32
33	- Supports a variable range of horizontal and vertical resolution and
34	  vertical refresh rates if the VESA Generalized Timing Formula is
35	  enabled.
36
37	- Supports color depths of 8, 16, 24 and 32 bits per pixel
38
39	- Supports pseudocolor, directcolor, or truecolor visuals
40
41	- Full and optimized hardware acceleration at 8, 16 and 24 bpp
42
43	- Robust video state save and restore
44
45	- MTRR support
46
47	- Utilizes user-entered monitor specifications to automatically
48	  calculate required video mode parameters.
49
50	- Can concurrently run with xfree86 running with native i810 drivers
51
52	- Hardware Cursor Support
53
54	- Supports EDID probing either by DDC/I2C or through the BIOS
55
56C.  List of available options
57=============================
58
59   a. "video=i810fb"
60	enables the i810 driver
61
62	Recommendation: required
63
64   b. "xres:<value>"
65	select horizontal resolution in pixels. (This parameter will be
66	ignored if 'mode_option' is specified.  See 'o' below).
67
68	Recommendation: user preference
69	(default = 640)
70
71   c. "yres:<value>"
72	select vertical resolution in scanlines. If Discrete Video Timings
73	is enabled, this will be ignored and computed as 3*xres/4.  (This
74	parameter will be ignored if 'mode_option' is specified.  See 'o'
75	below)
76
77	Recommendation: user preference
78	(default = 480)
79
80   d. "vyres:<value>"
81	select virtual vertical resolution in scanlines. If (0) or none
82	is specified, this will be computed against maximum available memory.
83
84	Recommendation: do not set
85	(default = 480)
86
87   e. "vram:<value>"
88	select amount of system RAM in MB to allocate for the video memory
89
90	Recommendation: 1 - 4 MB.
91	(default = 4)
92
93   f. "bpp:<value>"
94	select desired pixel depth
95
96	Recommendation: 8
97	(default = 8)
98
99   g. "hsync1/hsync2:<value>"
100	select the minimum and maximum Horizontal Sync Frequency of the
101	monitor in kHz.  If using a fixed frequency monitor, hsync1 must
102	be equal to hsync2. If EDID probing is successful, these will be
103	ignored and values will be taken from the EDID block.
104
105	Recommendation: check monitor manual for correct values
106	(default = 29/30)
107
108   h. "vsync1/vsync2:<value>"
109	select the minimum and maximum Vertical Sync Frequency of the monitor
110	in Hz. You can also use this option to lock your monitor's refresh
111	rate. If EDID probing is successful, these will be ignored and values
112	will be taken from the EDID block.
113
114	Recommendation: check monitor manual for correct values
115	(default = 60/60)
116
117	IMPORTANT:  If you need to clamp your timings, try to give some
118	leeway for computational errors (over/underflows).  Example: if
119	using vsync1/vsync2 = 60/60, make sure hsync1/hsync2 has at least
120	a 1 unit difference, and vice versa.
121
122   i. "voffset:<value>"
123	select at what offset in MB of the logical memory to allocate the
124	framebuffer memory.  The intent is to avoid the memory blocks
125	used by standard graphics applications (XFree86).  The default
126	offset (16 MB for a 64 MB aperture, 8 MB for a 32 MB aperture) will
127	avoid XFree86's usage and allows up to 7 MB/15 MB of framebuffer
128	memory.  Depending on your usage, adjust the value up or down
129	(0 for maximum usage, 31/63 MB for the least amount).  Note, an
130	arbitrary setting may conflict with XFree86.
131
132	Recommendation: do not set
133	(default = 8 or 16 MB)
134
135   j. "accel"
136	enable text acceleration.  This can be enabled/reenabled anytime
137	by using 'fbset -accel true/false'.
138
139	Recommendation: enable
140	(default = not set)
141
142   k. "mtrr"
143	enable MTRR.  This allows data transfers to the framebuffer memory
144	to occur in bursts which can significantly increase performance.
145	Not very helpful with the i810/i815 because of 'shared memory'.
146
147	Recommendation: do not set
148	(default = not set)
149
150   l. "extvga"
151	if specified, secondary/external VGA output will always be enabled.
152	Useful if the BIOS turns off the VGA port when no monitor is attached.
153	The external VGA monitor can then be attached without rebooting.
154
155	Recommendation: do not set
156	(default = not set)
157
158   m. "sync"
159	Forces the hardware engine to do a "sync" or wait for the hardware
160	to finish before starting another instruction. This will produce a
161	more stable setup, but will be slower.
162
163	Recommendation: do not set
164	(default = not set)
165
166   n. "dcolor"
167	Use directcolor visual instead of truecolor for pixel depths greater
168	than 8 bpp.  Useful for color tuning, such as gamma control.
169
170	Recommendation: do not set
171	(default = not set)
172
173   o. <xres>x<yres>[-<bpp>][@<refresh>]
174	The driver will now accept specification of boot mode option.  If this
175	is specified, the options 'xres' and 'yres' will be ignored. See
176	Documentation/fb/modedb.rst for usage.
177
178D. Kernel booting
179=================
180
181Separate each option/option-pair by commas (,) and the option from its value
182with a colon (:) as in the following::
183
184	video=i810fb:option1,option2:value2
185
186Sample Usage
187------------
188
189In /etc/lilo.conf, add the line::
190
191  append="video=i810fb:vram:2,xres:1024,yres:768,bpp:8,hsync1:30,hsync2:55, \
192	  vsync1:50,vsync2:85,accel,mtrr"
193
194This will initialize the framebuffer to 1024x768 at 8bpp.  The framebuffer
195will use 2 MB of System RAM. MTRR support will be enabled. The refresh rate
196will be computed based on the hsync1/hsync2 and vsync1/vsync2 values.
197
198IMPORTANT:
199  You must include hsync1, hsync2, vsync1 and vsync2 to enable video modes
200  better than 640x480 at 60Hz. HOWEVER, if your chipset/display combination
201  supports I2C and has an EDID block, you can safely exclude hsync1, hsync2,
202  vsync1 and vsync2 parameters.  These parameters will be taken from the EDID
203  block.
204
205E.  Module options
206==================
207
208The module parameters are essentially similar to the kernel
209parameters. The main difference is that you need to include a Boolean value
210(1 for TRUE, and 0 for FALSE) for those options which don't need a value.
211
212Example, to enable MTRR, include "mtrr=1".
213
214Sample Usage
215------------
216
217Using the same setup as described above, load the module like this::
218
219	modprobe i810fb vram=2 xres=1024 bpp=8 hsync1=30 hsync2=55 vsync1=50 \
220		 vsync2=85 accel=1 mtrr=1
221
222Or just add the following to a configuration file in /etc/modprobe.d/::
223
224	options i810fb vram=2 xres=1024 bpp=16 hsync1=30 hsync2=55 vsync1=50 \
225	vsync2=85 accel=1 mtrr=1
226
227and just do a::
228
229	modprobe i810fb
230
231
232F.  Setup
233=========
234
235	a. Do your usual method of configuring the kernel
236
237	   make menuconfig/xconfig/config
238
239	b. Under "Code maturity level options" enable "Prompt for development
240	   and/or incomplete code/drivers".
241
242	c. Enable agpgart support for the Intel 810/815 on-board graphics.
243	   This is required.  The option is under "Character Devices".
244
245	d. Under "Graphics Support", select "Intel 810/815" either statically
246	   or as a module.  Choose "use VESA Generalized Timing Formula" if
247	   you need to maximize the capability of your display.  To be on the
248	   safe side, you can leave this unselected.
249
250	e. If you want support for DDC/I2C probing (Plug and Play Displays),
251	   set 'Enable DDC Support' to 'y'. To make this option appear, set
252	   'use VESA Generalized Timing Formula' to 'y'.
253
254	f. If you want a framebuffer console, enable it under "Console
255	   Drivers".
256
257	g. Compile your kernel.
258
259	h. Load the driver as described in sections D and E.
260
261	i.  Try the DirectFB (http://www.directfb.org) + the i810 gfxdriver
262	    patch to see the chipset in action (or inaction :-).
263
264G.  Acknowledgment:
265===================
266
267	1.  Geert Uytterhoeven - his excellent howto and the virtual
268	    framebuffer driver code made this possible.
269
270	2.  Jeff Hartmann for his agpgart code.
271
272	3.  The X developers.  Insights were provided just by reading the
273	    XFree86 source code.
274
275	4.  Intel(c).  For this value-oriented chipset driver and for
276	    providing documentation.
277
278	5. Matt Sottek.  His inputs and ideas  helped in making some
279	   optimizations possible.
280
281H.  Home Page:
282==============
283
284	A more complete, and probably updated information is provided at
285	http://i810fb.sourceforge.net.
286
287Tony
288