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-rw-r--r--Documentation/fb/cyblafb/bugs14
-rw-r--r--Documentation/fb/cyblafb/credits7
-rw-r--r--Documentation/fb/cyblafb/documentation17
-rw-r--r--Documentation/fb/cyblafb/fb.modes155
-rw-r--r--Documentation/fb/cyblafb/performance80
-rw-r--r--Documentation/fb/cyblafb/todo32
-rw-r--r--Documentation/fb/cyblafb/usage206
-rw-r--r--Documentation/fb/cyblafb/whycyblafb85
-rw-r--r--Documentation/fb/modedb.txt73
9 files changed, 668 insertions, 1 deletions
diff --git a/Documentation/fb/cyblafb/bugs b/Documentation/fb/cyblafb/bugs
new file mode 100644
index 000000000000..f90cc66ea919
--- /dev/null
+++ b/Documentation/fb/cyblafb/bugs
@@ -0,0 +1,14 @@
1Bugs
2====
3
4I currently don't know of any bug. Please do send reports to:
5 - linux-fbdev-devel@lists.sourceforge.net
6 - Knut_Petersen@t-online.de.
7
8
9Untested features
10=================
11
12All LCD stuff is untested. If it worked in tridentfb, it should work in
13cyblafb. Please test and report the results to Knut_Petersen@t-online.de.
14
diff --git a/Documentation/fb/cyblafb/credits b/Documentation/fb/cyblafb/credits
new file mode 100644
index 000000000000..0eb3b443dc2b
--- /dev/null
+++ b/Documentation/fb/cyblafb/credits
@@ -0,0 +1,7 @@
1Thanks to
2=========
3 * Alan Hourihane, for writing the X trident driver
4 * Jani Monoses, for writing the tridentfb driver
5 * Antonino A. Daplas, for review of the first published
6 version of cyblafb and some code
7 * Jochen Hein, for testing and a helpfull bug report
diff --git a/Documentation/fb/cyblafb/documentation b/Documentation/fb/cyblafb/documentation
new file mode 100644
index 000000000000..bb1aac048425
--- /dev/null
+++ b/Documentation/fb/cyblafb/documentation
@@ -0,0 +1,17 @@
1Available Documentation
2=======================
3
4Apollo PLE 133 Chipset VT8601A North Bridge Datasheet, Rev. 1.82, October 22,
52001, available from VIA:
6
7 http://www.viavpsd.com/product/6/15/DS8601A182.pdf
8
9The datasheet is incomplete, some registers that need to be programmed are not
10explained at all and important bits are listed as "reserved". But you really
11need the datasheet to understand the code. "p. xxx" comments refer to page
12numbers of this document.
13
14XFree/XOrg drivers are available and of good quality, looking at the code
15there is a good idea if the datasheet does not provide enough information
16or if the datasheet seems to be wrong.
17
diff --git a/Documentation/fb/cyblafb/fb.modes b/Documentation/fb/cyblafb/fb.modes
new file mode 100644
index 000000000000..cf4351fc32ff
--- /dev/null
+++ b/Documentation/fb/cyblafb/fb.modes
@@ -0,0 +1,155 @@
1#
2# Sample fb.modes file
3#
4# Provides an incomplete list of working modes for
5# the cyberblade/i1 graphics core.
6#
7# The value 4294967256 is used instead of -40. Of course, -40 is not
8# a really reasonable value, but chip design does not always follow
9# logic. Believe me, it's ok, and it's the way the BIOS does it.
10#
11# fbset requires 4294967256 in fb.modes and -40 as an argument to
12# the -t parameter. That's also not too reasonable, and it might change
13# in the future or might even be differt for your current version.
14#
15
16mode "640x480-50"
17 geometry 640 480 640 3756 8
18 timings 47619 4294967256 24 17 0 216 3
19endmode
20
21mode "640x480-60"
22 geometry 640 480 640 3756 8
23 timings 39682 4294967256 24 17 0 216 3
24endmode
25
26mode "640x480-70"
27 geometry 640 480 640 3756 8
28 timings 34013 4294967256 24 17 0 216 3
29endmode
30
31mode "640x480-72"
32 geometry 640 480 640 3756 8
33 timings 33068 4294967256 24 17 0 216 3
34endmode
35
36mode "640x480-75"
37 geometry 640 480 640 3756 8
38 timings 31746 4294967256 24 17 0 216 3
39endmode
40
41mode "640x480-80"
42 geometry 640 480 640 3756 8
43 timings 29761 4294967256 24 17 0 216 3
44endmode
45
46mode "640x480-85"
47 geometry 640 480 640 3756 8
48 timings 28011 4294967256 24 17 0 216 3
49endmode
50
51mode "800x600-50"
52 geometry 800 600 800 3221 8
53 timings 30303 96 24 14 0 136 11
54endmode
55
56mode "800x600-60"
57 geometry 800 600 800 3221 8
58 timings 25252 96 24 14 0 136 11
59endmode
60
61mode "800x600-70"
62 geometry 800 600 800 3221 8
63 timings 21645 96 24 14 0 136 11
64endmode
65
66mode "800x600-72"
67 geometry 800 600 800 3221 8
68 timings 21043 96 24 14 0 136 11
69endmode
70
71mode "800x600-75"
72 geometry 800 600 800 3221 8
73 timings 20202 96 24 14 0 136 11
74endmode
75
76mode "800x600-80"
77 geometry 800 600 800 3221 8
78 timings 18939 96 24 14 0 136 11
79endmode
80
81mode "800x600-85"
82 geometry 800 600 800 3221 8
83 timings 17825 96 24 14 0 136 11
84endmode
85
86mode "1024x768-50"
87 geometry 1024 768 1024 2815 8
88 timings 19054 144 24 29 0 120 3
89endmode
90
91mode "1024x768-60"
92 geometry 1024 768 1024 2815 8
93 timings 15880 144 24 29 0 120 3
94endmode
95
96mode "1024x768-70"
97 geometry 1024 768 1024 2815 8
98 timings 13610 144 24 29 0 120 3
99endmode
100
101mode "1024x768-72"
102 geometry 1024 768 1024 2815 8
103 timings 13232 144 24 29 0 120 3
104endmode
105
106mode "1024x768-75"
107 geometry 1024 768 1024 2815 8
108 timings 12703 144 24 29 0 120 3
109endmode
110
111mode "1024x768-80"
112 geometry 1024 768 1024 2815 8
113 timings 11910 144 24 29 0 120 3
114endmode
115
116mode "1024x768-85"
117 geometry 1024 768 1024 2815 8
118 timings 11209 144 24 29 0 120 3
119endmode
120
121mode "1280x1024-50"
122 geometry 1280 1024 1280 2662 8
123 timings 11114 232 16 39 0 160 3
124endmode
125
126mode "1280x1024-60"
127 geometry 1280 1024 1280 2662 8
128 timings 9262 232 16 39 0 160 3
129endmode
130
131mode "1280x1024-70"
132 geometry 1280 1024 1280 2662 8
133 timings 7939 232 16 39 0 160 3
134endmode
135
136mode "1280x1024-72"
137 geometry 1280 1024 1280 2662 8
138 timings 7719 232 16 39 0 160 3
139endmode
140
141mode "1280x1024-75"
142 geometry 1280 1024 1280 2662 8
143 timings 7410 232 16 39 0 160 3
144endmode
145
146mode "1280x1024-80"
147 geometry 1280 1024 1280 2662 8
148 timings 6946 232 16 39 0 160 3
149endmode
150
151mode "1280x1024-85"
152 geometry 1280 1024 1280 2662 8
153 timings 6538 232 16 39 0 160 3
154endmode
155
diff --git a/Documentation/fb/cyblafb/performance b/Documentation/fb/cyblafb/performance
new file mode 100644
index 000000000000..eb4e47a9cea6
--- /dev/null
+++ b/Documentation/fb/cyblafb/performance
@@ -0,0 +1,80 @@
1Speed
2=====
3
4CyBlaFB is much faster than tridentfb and vesafb. Compare the performance data
5for mode 1280x1024-[8,16,32]@61 Hz.
6
7Test 1: Cat a file with 2000 lines of 0 characters.
8Test 2: Cat a file with 2000 lines of 80 characters.
9Test 3: Cat a file with 2000 lines of 160 characters.
10
11All values show system time use in seconds, kernel 2.6.12 was used for
12the measurements. 2.6.13 is a bit slower, 2.6.14 hopefully will include a
13patch that speeds up kernel bitblitting a lot ( > 20%).
14
15+-----------+-----------------------------------------------------+
16| | not accelerated |
17| TRIDENTFB +-----------------+-----------------+-----------------+
18| of 2.6.12 | 8 bpp | 16 bpp | 32 bpp |
19| | noypan | ypan | noypan | ypan | noypan | ypan |
20+-----------+--------+--------+--------+--------+--------+--------+
21| Test 1 | 4.31 | 4.33 | 6.05 | 12.81 | ---- | ---- |
22| Test 2 | 67.94 | 5.44 | 123.16 | 14.79 | ---- | ---- |
23| Test 3 | 131.36 | 6.55 | 240.12 | 16.76 | ---- | ---- |
24+-----------+--------+--------+--------+--------+--------+--------+
25| Comments | | | completely bro- |
26| | | | ken, monitor |
27| | | | switches off |
28+-----------+-----------------+-----------------+-----------------+
29
30
31+-----------+-----------------------------------------------------+
32| | accelerated |
33| TRIDENTFB +-----------------+-----------------+-----------------+
34| of 2.6.12 | 8 bpp | 16 bpp | 32 bpp |
35| | noypan | ypan | noypan | ypan | noypan | ypan |
36+-----------+--------+--------+--------+--------+--------+--------+
37| Test 1 | ---- | ---- | 20.62 | 1.22 | ---- | ---- |
38| Test 2 | ---- | ---- | 22.61 | 3.19 | ---- | ---- |
39| Test 3 | ---- | ---- | 24.59 | 5.16 | ---- | ---- |
40+-----------+--------+--------+--------+--------+--------+--------+
41| Comments | broken, writing | broken, ok only | completely bro- |
42| | to wrong places | if bgcolor is | ken, monitor |
43| | on screen + bug | black, bug in | switches off |
44| | in fillrect() | fillrect() | |
45+-----------+-----------------+-----------------+-----------------+
46
47
48+-----------+-----------------------------------------------------+
49| | not accelerated |
50| VESAFB +-----------------+-----------------+-----------------+
51| of 2.6.12 | 8 bpp | 16 bpp | 32 bpp |
52| | noypan | ypan | noypan | ypan | noypan | ypan |
53+-----------+--------+--------+--------+--------+--------+--------+
54| Test 1 | 4.26 | 3.76 | 5.99 | 7.23 | ---- | ---- |
55| Test 2 | 65.65 | 4.89 | 120.88 | 9.08 | ---- | ---- |
56| Test 3 | 126.91 | 5.94 | 235.77 | 11.03 | ---- | ---- |
57+-----------+--------+--------+--------+--------+--------+--------+
58| Comments | vga=0x307 | vga=0x31a | vga=0x31b not |
59| | fh=80kHz | fh=80kHz | supported by |
60| | fv=75kHz | fv=75kHz | video BIOS and |
61| | | | hardware |
62+-----------+-----------------+-----------------+-----------------+
63
64
65+-----------+-----------------------------------------------------+
66| | accelerated |
67| CYBLAFB +-----------------+-----------------+-----------------+
68| | 8 bpp | 16 bpp | 32 bpp |
69| | noypan | ypan | noypan | ypan | noypan | ypan |
70+-----------+--------+--------+--------+--------+--------+--------+
71| Test 1 | 8.02 | 0.23 | 19.04 | 0.61 | 57.12 | 2.74 |
72| Test 2 | 8.38 | 0.55 | 19.39 | 0.92 | 57.54 | 3.13 |
73| Test 3 | 8.73 | 0.86 | 19.74 | 1.24 | 57.95 | 3.51 |
74+-----------+--------+--------+--------+--------+--------+--------+
75| Comments | | | |
76| | | | |
77| | | | |
78| | | | |
79+-----------+-----------------+-----------------+-----------------+
80
diff --git a/Documentation/fb/cyblafb/todo b/Documentation/fb/cyblafb/todo
new file mode 100644
index 000000000000..80fb2f89b6c1
--- /dev/null
+++ b/Documentation/fb/cyblafb/todo
@@ -0,0 +1,32 @@
1TODO / Missing features
2=======================
3
4Verify LCD stuff "stretch" and "center" options are
5 completely untested ... this code needs to be
6 verified. As I don't have access to such
7 hardware, please contact me if you are
8 willing run some tests.
9
10Interlaced video modes The reason that interleaved
11 modes are disabled is that I do not know
12 the meaning of the vertical interlace
13 parameter. Also the datasheet mentions a
14 bit d8 of a horizontal interlace parameter,
15 but nowhere the lower 8 bits. Please help
16 if you can.
17
18low-res double scan modes Who needs it?
19
20accelerated color blitting Who needs it? The console driver does use color
21 blitting for nothing but drawing the penguine,
22 everything else is done using color expanding
23 blitting of 1bpp character bitmaps.
24
25xpanning Who needs it?
26
27ioctls Who needs it?
28
29TV-out Will be done later
30
31??? Feel free to contact me if you have any
32 feature requests
diff --git a/Documentation/fb/cyblafb/usage b/Documentation/fb/cyblafb/usage
new file mode 100644
index 000000000000..e627c8f54211
--- /dev/null
+++ b/Documentation/fb/cyblafb/usage
@@ -0,0 +1,206 @@
1CyBlaFB is a framebuffer driver for the Cyberblade/i1 graphics core integrated
2into the VIA Apollo PLE133 (aka vt8601) south bridge. It is developed and
3tested using a VIA EPIA 5000 board.
4
5Cyblafb - compiled into the kernel or as a module?
6==================================================
7
8You might compile cyblafb either as a module or compile it permanently into the
9kernel.
10
11Unless you have a real reason to do so you should not compile both vesafb and
12cyblafb permanently into the kernel. It's possible and it helps during the
13developement cycle, but it's useless and will at least block some otherwise
14usefull memory for ordinary users.
15
16Selecting Modes
17===============
18
19 Startup Mode
20 ============
21
22 First of all, you might use the "vga=???" boot parameter as it is
23 documented in vesafb.txt and svga.txt. Cyblafb will detect the video
24 mode selected and will use the geometry and timings found by
25 inspecting the hardware registers.
26
27 video=cyblafb vga=0x317
28
29 Alternatively you might use a combination of the mode, ref and bpp
30 parameters. If you compiled the driver into the kernel, add something
31 like this to the kernel command line:
32
33 video=cyblafb:1280x1024,bpp=16,ref=50 ...
34
35 If you compiled the driver as a module, the same mode would be
36 selected by the following command:
37
38 modprobe cyblafb mode=1280x1024 bpp=16 ref=50 ...
39
40 None of the modes possible to select as startup modes are affected by
41 the problems described at the end of the next subsection.
42
43 Mode changes using fbset
44 ========================
45
46 You might use fbset to change the video mode, see "man fbset". Cyblafb
47 generally does assume that you know what you are doing. But it does
48 some checks, especially those that are needed to prevent you from
49 damaging your hardware.
50
51 - only 8, 16, 24 and 32 bpp video modes are accepted
52 - interlaced video modes are not accepted
53 - double scan video modes are not accepted
54 - if a flat panel is found, cyblafb does not allow you
55 to program a resolution higher than the physical
56 resolution of the flat panel monitor
57 - cyblafb does not allow xres to differ from xres_virtual
58 - cyblafb does not allow vclk to exceed 230 MHz. As 32 bpp
59 and (currently) 24 bit modes use a doubled vclk internally,
60 the dotclock limit as seen by fbset is 115 MHz for those
61 modes and 230 MHz for 8 and 16 bpp modes.
62
63 Any request that violates the rules given above will be ignored and
64 fbset will return an error.
65
66 If you program a virtual y resolution higher than the hardware limit,
67 cyblafb will silently decrease that value to the highest possible
68 value.
69
70 Attempts to disable acceleration are ignored.
71
72 Some video modes that should work do not work as expected. If you use
73 the standard fb.modes, fbset 640x480-60 will program that mode, but
74 you will see a vertical area, about two characters wide, with only
75 much darker characters than the other characters on the screen.
76 Cyblafb does allow that mode to be set, as it does not violate the
77 official specifications. It would need a lot of code to reliably sort
78 out all invalid modes, playing around with the margin values will
79 give a valid mode quickly. And if cyblafb would detect such an invalid
80 mode, should it silently alter the requested values or should it
81 report an error? Both options have some pros and cons. As stated
82 above, none of the startup modes are affected, and if you set
83 verbosity to 1 or higher, cyblafb will print the fbset command that
84 would be needed to program that mode using fbset.
85
86
87Other Parameters
88================
89
90
91crt don't autodetect, assume monitor connected to
92 standard VGA connector
93
94fp don't autodetect, assume flat panel display
95 connected to flat panel monitor interface
96
97nativex inform driver about native x resolution of
98 flat panel monitor connected to special
99 interface (should be autodetected)
100
101stretch stretch image to adapt low resolution modes to
102 higer resolutions of flat panel monitors
103 connected to special interface
104
105center center image to adapt low resolution modes to
106 higer resolutions of flat panel monitors
107 connected to special interface
108
109memsize use if autodetected memsize is wrong ...
110 should never be necessary
111
112nopcirr disable PCI read retry
113nopciwr disable PCI write retry
114nopcirb disable PCI read bursts
115nopciwb disable PCI write bursts
116
117bpp bpp for specified modes
118 valid values: 8 || 16 || 24 || 32
119
120ref refresh rate for specified mode
121 valid values: 50 <= ref <= 85
122
123mode 640x480 or 800x600 or 1024x768 or 1280x1024
124 if not specified, the startup mode will be detected
125 and used, so you might also use the vga=??? parameter
126 described in vesafb.txt. If you do not specify a mode,
127 bpp and ref parameters are ignored.
128
129verbosity 0 is the default, increase to at least 2 for every
130 bug report!
131
132vesafb allows cyblafb to be loaded after vesafb has been
133 loaded. See sections "Module unloading ...".
134
135
136Development hints
137=================
138
139It's much faster do compile a module and to load the new version after
140unloading the old module than to compile a new kernel and to reboot. So if you
141try to work on cyblafb, it might be a good idea to use cyblafb as a module.
142In real life, fast often means dangerous, and that's also the case here. If
143you introduce a serious bug when cyblafb is compiled into the kernel, the
144kernel will lock or oops with a high probability before the file system is
145mounted, and the danger for your data is low. If you load a broken own version
146of cyblafb on a running system, the danger for the integrity of the file
147system is much higher as you might need a hard reset afterwards. Decide
148yourself.
149
150Module unloading, the vfb method
151================================
152
153If you want to unload/reload cyblafb using the virtual framebuffer, you need
154to enable vfb support in the kernel first. After that, load the modules as
155shown below:
156
157 modprobe vfb vfb_enable=1
158 modprobe fbcon
159 modprobe cyblafb
160 fbset -fb /dev/fb1 1280x1024-60 -vyres 2662
161 con2fb /dev/fb1 /dev/tty1
162 ...
163
164If you now made some changes to cyblafb and want to reload it, you might do it
165as show below:
166
167 con2fb /dev/fb0 /dev/tty1
168 ...
169 rmmod cyblafb
170 modprobe cyblafb
171 con2fb /dev/fb1 /dev/tty1
172 ...
173
174Of course, you might choose another mode, and most certainly you also want to
175map some other /dev/tty* to the real framebuffer device. You might also choose
176to compile fbcon as a kernel module or place it permanently in the kernel.
177
178I do not know of any way to unload fbcon, and fbcon will prevent the
179framebuffer device loaded first from unloading. [If there is a way, then
180please add a description here!]
181
182Module unloading, the vesafb method
183===================================
184
185Configure the kernel:
186
187 <*> Support for frame buffer devices
188 [*] VESA VGA graphics support
189 <M> Cyberblade/i1 support
190
191Add e.g. "video=vesafb:ypan vga=0x307" to the kernel parameters. The ypan
192parameter is important, choose any vga parameter you like as long as it is
193a graphics mode.
194
195After booting, load cyblafb without any mode and bpp parameter and assign
196cyblafb to individual ttys using con2fb, e.g.:
197
198 modprobe cyblafb vesafb=1
199 con2fb /dev/fb1 /dev/tty1
200
201Unloading cyblafb works without problems after you assign vesafb to all
202ttys again, e.g.:
203
204 con2fb /dev/fb0 /dev/tty1
205 rmmod cyblafb
206
diff --git a/Documentation/fb/cyblafb/whycyblafb b/Documentation/fb/cyblafb/whycyblafb
new file mode 100644
index 000000000000..a123bc11e698
--- /dev/null
+++ b/Documentation/fb/cyblafb/whycyblafb
@@ -0,0 +1,85 @@
1I tried the following framebuffer drivers:
2
3 - TRIDENTFB is full of bugs. Acceleration is broken for Blade3D
4 graphics cores like the cyberblade/i1. It claims to support a great
5 number of devices, but documentation for most of these devices is
6 unfortunately not available. There is _no_ reason to use tridentfb
7 for cyberblade/i1 + CRT users. VESAFB is faster, and the one
8 advantage, mode switching, is broken in tridentfb.
9
10 - VESAFB is used by many distributions as a standard. Vesafb does
11 not support mode switching. VESAFB is a bit faster than the working
12 configurations of TRIDENTFB, but it is still too slow, even if you
13 use ypan.
14
15 - EPIAFB (you'll find it on sourceforge) supports the Cyberblade/i1
16 graphics core, but it still has serious bugs and developement seems
17 to have stopped. This is the one driver with TV-out support. If you
18 do need this feature, try epiafb.
19
20None of these drivers was a real option for me.
21
22I believe that is unreasonable to change code that announces to support 20
23devices if I only have more or less sufficient documentation for exactly one
24of these. The risk of breaking device foo while fixing device bar is too high.
25
26So I decided to start CyBlaFB as a stripped down tridentfb.
27
28All code specific to other Trident chips has been removed. After that there
29were a lot of cosmetic changes to increase the readability of the code. All
30register names were changed to those mnemonics used in the datasheet. Function
31and macro names were changed if they hindered easy understanding of the code.
32
33After that I debugged the code and implemented some new features. I'll try to
34give a little summary of the main changes:
35
36 - calculation of vertical and horizontal timings was fixed
37
38 - video signal quality has been improved dramatically
39
40 - acceleration:
41
42 - fillrect and copyarea were fixed and reenabled
43
44 - color expanding imageblit was newly implemented, color
45 imageblit (only used to draw the penguine) still uses the
46 generic code.
47
48 - init of the acceleration engine was improved and moved to a
49 place where it really works ...
50
51 - sync function has a timeout now and tries to reset and
52 reinit the accel engine if necessary
53
54 - fewer slow copyarea calls when doing ypan scrolling by using
55 undocumented bit d21 of screen start address stored in
56 CR2B[5]. BIOS does use it also, so this should be safe.
57
58 - cyblafb rejects any attempt to set modes that would cause vclk
59 values above reasonable 230 MHz. 32bit modes use a clock
60 multiplicator of 2, so fbset does show the correct values for
61 pixclock but not for vclk in this case. The fbset limit is 115 MHz
62 for 32 bpp modes.
63
64 - cyblafb rejects modes known to be broken or unimplemented (all
65 interlaced modes, all doublescan modes for now)
66
67 - cyblafb now works independant of the video mode in effect at startup
68 time (tridentfb does not init all needed registers to reasonable
69 values)
70
71 - switching between video modes does work reliably now
72
73 - the first video mode now is the one selected on startup using the
74 vga=???? mechanism or any of
75 - 640x480, 800x600, 1024x768, 1280x1024
76 - 8, 16, 24 or 32 bpp
77 - refresh between 50 Hz and 85 Hz, 1 Hz steps (1280x1024-32
78 is limited to 63Hz)
79
80 - pci retry and pci burst mode are settable (try to disable if you
81 experience latency problems)
82
83 - built as a module cyblafb might be unloaded and reloaded using
84 the vfb module and con2vt or might be used together with vesafb
85
diff --git a/Documentation/fb/modedb.txt b/Documentation/fb/modedb.txt
index e04458b319d5..4fcdb4cf4cca 100644
--- a/Documentation/fb/modedb.txt
+++ b/Documentation/fb/modedb.txt
@@ -20,12 +20,83 @@ in a video= option, fbmem considers that to be a global video mode option.
20 20
21Valid mode specifiers (mode_option argument): 21Valid mode specifiers (mode_option argument):
22 22
23 <xres>x<yres>[-<bpp>][@<refresh>] 23 <xres>x<yres>[M][R][-<bpp>][@<refresh>][i][m]
24 <name>[-<bpp>][@<refresh>] 24 <name>[-<bpp>][@<refresh>]
25 25
26with <xres>, <yres>, <bpp> and <refresh> decimal numbers and <name> a string. 26with <xres>, <yres>, <bpp> and <refresh> decimal numbers and <name> a string.
27Things between square brackets are optional. 27Things between square brackets are optional.
28 28
29If 'M' is specified in the mode_option argument (after <yres> and before
30<bpp> and <refresh>, if specified) the timings will be calculated using
31VESA(TM) Coordinated Video Timings instead of looking up the mode from a table.
32If 'R' is specified, do a 'reduced blanking' calculation for digital displays.
33If 'i' is specified, calculate for an interlaced mode. And if 'm' is
34specified, add margins to the calculation (1.8% of xres rounded down to 8
35pixels and 1.8% of yres).
36
37 Sample usage: 1024x768M@60m - CVT timing with margins
38
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40
41What is the VESA(TM) Coordinated Video Timings (CVT)?
42
43From the VESA(TM) Website:
44
45 "The purpose of CVT is to provide a method for generating a consistent
46 and coordinated set of standard formats, display refresh rates, and
47 timing specifications for computer display products, both those
48 employing CRTs, and those using other display technologies. The
49 intention of CVT is to give both source and display manufacturers a
50 common set of tools to enable new timings to be developed in a
51 consistent manner that ensures greater compatibility."
52
53This is the third standard approved by VESA(TM) concerning video timings. The
54first was the Discrete Video Timings (DVT) which is a collection of
55pre-defined modes approved by VESA(TM). The second is the Generalized Timing
56Formula (GTF) which is an algorithm to calculate the timings, given the
57pixelclock, the horizontal sync frequency, or the vertical refresh rate.
58
59The GTF is limited by the fact that it is designed mainly for CRT displays.
60It artificially increases the pixelclock because of its high blanking
61requirement. This is inappropriate for digital display interface with its high
62data rate which requires that it conserves the pixelclock as much as possible.
63Also, GTF does not take into account the aspect ratio of the display.
64
65The CVT addresses these limitations. If used with CRT's, the formula used
66is a derivation of GTF with a few modifications. If used with digital
67displays, the "reduced blanking" calculation can be used.
68
69From the framebuffer subsystem perspective, new formats need not be added
70to the global mode database whenever a new mode is released by display
71manufacturers. Specifying for CVT will work for most, if not all, relatively
72new CRT displays and probably with most flatpanels, if 'reduced blanking'
73calculation is specified. (The CVT compatibility of the display can be
74determined from its EDID. The version 1.3 of the EDID has extra 128-byte
75blocks where additional timing information is placed. As of this time, there
76is no support yet in the layer to parse this additional blocks.)
77
78CVT also introduced a new naming convention (should be seen from dmesg output):
79
80 <pix>M<a>[-R]
81
82 where: pix = total amount of pixels in MB (xres x yres)
83 M = always present
84 a = aspect ratio (3 - 4:3; 4 - 5:4; 9 - 15:9, 16:9; A - 16:10)
85 -R = reduced blanking
86
87 example: .48M3-R - 800x600 with reduced blanking
88
89Note: VESA(TM) has restrictions on what is a standard CVT timing:
90
91 - aspect ratio can only be one of the above values
92 - acceptable refresh rates are 50, 60, 70 or 85 Hz only
93 - if reduced blanking, the refresh rate must be at 60Hz
94
95If one of the above are not satisfied, the kernel will print a warning but the
96timings will still be calculated.
97
98***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo ***** oOo *****
99
29To find a suitable video mode, you just call 100To find a suitable video mode, you just call
30 101
31int __init fb_find_mode(struct fb_var_screeninfo *var, 102int __init fb_find_mode(struct fb_var_screeninfo *var,
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