1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
|
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style type="text/css">
@import url('../css/main.css');
</style>
<title>ThinkPad T500</title>
</head>
<body>
<div class="section">
<h1 id="pagetop">LCD compatibility on GM45 laptops</h1>
<p>
On the T400 and T500 (maybe others), some of the higher resolution panels
(e.g. 1440x900, 1680x1050, 1920x1200) fail in libreboot.
</p>
<p>
NOTE: All X200/X200S/X200T LCD panels are believed to be compatible.
</p>
<p>
<a href="index.html">Back to previous index</a>.
</p>
</div>
<div class="section">
<h1>The problem</h1>
<p>
In some cases, backlight turns on during boot, sometimes not. In all cases,
no display is shown in GRUB, nor in GNU/Linux.
</p>
<h1>
Current workaround:
</h1>
<p>
T500/R400 are clones of the T400. See <b>coreboot/src/mainboard/lenovo/t400/devicetree.cb</b> in libreboot,
and note that <b>register "gfx.lvds_dual_channel" = "0"</b> - in other words, single channel LVDS mode is
enforced. This works on the lower resolution panels (1280x800), but not on the higher ones.
</p>
<p>
For the high-res panels, re-compiling with <b>register "gfx.lvds_dual_channel" = "1"</b> partially solves
the problem for those displays; there is still no display in GRUB, but once the kernel takes over, there
is a display.
</p>
<p>
Linux (kernel) has its own init code (including EDID parsing). The current suspicion is that coreboot's
own initialization code has buggy EDID parsing in some way, such that the proper settings for the panel
are not used, leading to the failure. The actual graphics initialization does work.
</p>
</div>
<div class="section">
<h2 id="edid">EDID</h2>
<p>
One T500 had a screen (1920x1200) that is currently incompatible. Working to fix it. EDID:
</p>
<pre>
user@user-ThinkPad-T500:~/Desktop$ sudo i2cdump -y 2 0x50
No size specified (using byte-data access)
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef
00: XX ff ff ff ff ff ff 00 30 ae 55 40 00 00 00 00 X.......0?U@....
10: 00 11 01 03 80 21 15 78 ea ba 70 98 59 52 8c 28 .????!?x??p?YR?(
20: 25 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01 %PT...??????????
30: 01 01 01 01 01 01 e7 3a 80 8c 70 b0 14 40 1e 50 ???????:??p??@?P
40: 24 00 4b cf 10 00 00 19 16 31 80 8c 70 b0 14 40 $.K??..??1??p??@
50: 1e 50 24 00 4b cf 10 00 00 19 00 00 00 0f 00 d1 ?P$.K??..?...?.?
60: 0a 32 d1 0a 28 11 01 00 32 0c 00 00 00 00 00 fe ?2??(??.2?.....?
70: 00 4c 50 31 35 34 57 55 31 2d 54 4c 42 31 00 9a .LP154WU1-TLB1.?
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................
</pre>
<p>
What happens: backlight turns on at boot, then turns off. At no point is there
a working visual display.
</p>
<p>
Another incompatible screen (EDID) 1680 x 1050 with the same issue:
</p>
<pre>
EDID:
00 ff ff ff ff ff ff 00 30 ae 53 40 00 00 00 00
00 11 01 03 80 21 15 78 ea cd 75 91 55 4f 8b 26
21 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 a8 2f 90 e0 60 1a 10 40 20 40
13 00 4b cf 10 00 00 19 b7 27 90 e0 60 1a 10 40
20 40 13 00 4b cf 10 00 00 19 00 00 00 0f 00 b3
0a 32 b3 0a 28 14 01 00 4c a3 50 33 00 00 00 fe
00 4c 54 4e 31 35 34 50 33 2d 4c 30 32 0a 00 7e
Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 30 ae 53 40 00 00 00 00 00 11
version: 01 03
basic params: 80 21 15 78 ea
chroma info: cd 75 91 55 4f 8b 26 21 50 54
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: a8 2f 90 e0 60 1a 10 40 20 40 13 00 4b cf 10 00 00 19
descriptor 2: b7 27 90 e0 60 1a 10 40 20 40 13 00 4b cf 10 00 00 19
descriptor 3: 00 00 00 0f 00 b3 0a 32 b3 0a 28 14 01 00 4c a3 50 33
descriptor 4: 00 00 00 fe 00 4c 54 4e 31 35 34 50 33 2d 4c 30 32 0a
extensions: 00
checksum: 7e
Manufacturer: LEN Model 4053 Serial Number 0
Made week 0 of 2007
EDID version: 1.3
Digital display
Maximum image size: 33 cm x 21 cm
Gamma: 220%
Check DPMS levels
DPMS levels: Standby Suspend Off
Supported color formats: RGB 4:4:4, YCrCb 4:2:2
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed timings
Hex of detail: a82f90e0601a1040204013004bcf10000019
Did detailed timing
Detailed mode (IN HEX): Clock 122000 KHz, 14b mm x cf mm
0690 06b0 06f0 0770 hborder 0
041a 041b 041e 042a vborder 0
-hsync -vsync
Hex of detail: b72790e0601a1040204013004bcf10000019
Detailed mode (IN HEX): Clock 122000 KHz, 14b mm x cf mm
0690 06b0 06f0 0770 hborder 0
041a 041b 041e 042a vborder 0
-hsync -vsync
Hex of detail: 0000000f00b30a32b30a281401004ca35033
Manufacturer-specified data, tag 15
Hex of detail: 000000fe004c544e31353450332d4c30320a
ASCII string: LTN154P3-L02
Checksum
Checksum: 0x7e (valid)
WARNING: EDID block does NOT fully conform to EDID 1.3.
Missing name descriptor
Missing monitor ranges
bringing up panel at resolution 1680 x 1050
Borders 0 x 0
Blank 224 x 16
Sync 64 x 3
Front porch 32 x 1
Spread spectrum clock
Single channel
Polarities 1, 1
Data M1=2132104, N1=8388608
Link frequency 270000 kHz
Link M1=236900, N1=524288
Pixel N=9, M1=24, M2=8, P1=1
Pixel clock 243809 kHz
waiting for panel powerup
panel powered up
</pre>
<p>
For comparison, here is a working display (T400 screen, but was
connected to a T500. Some T500 displays also work, but no EDID
available on this page yet):
</p>
<pre>
EDID:
00 ff ff ff ff ff ff 00 30 ae 31 40 00 00 00 00
00 12 01 03 80 1e 13 78 ea b3 85 95 58 53 8a 28
25 50 54 00 00 00 01 01 01 01 01 01 01 01 01 01
01 01 01 01 01 01 26 1b 00 7d 50 20 16 30 30 20
36 00 30 be 10 00 00 18 8b 16 00 7d 50 20 16 30
30 20 36 00 30 be 10 00 00 18 00 00 00 0f 00 81
0a 32 81 0a 28 14 01 00 30 e4 28 01 00 00 00 fe
00 4c 50 31 34 31 57 58 33 2d 54 4c 52 31 00 d8
Extracted contents:
header: 00 ff ff ff ff ff ff 00
serial number: 30 ae 31 40 00 00 00 00 00 12
version: 01 03
basic params: 80 1e 13 78 ea
chroma info: b3 85 95 58 53 8a 28 25 50 54
established: 00 00 00
standard: 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01 01
descriptor 1: 26 1b 00 7d 50 20 16 30 30 20 36 00 30 be 10 00 00 18
descriptor 2: 8b 16 00 7d 50 20 16 30 30 20 36 00 30 be 10 00 00 18
descriptor 3: 00 00 00 0f 00 81 0a 32 81 0a 28 14 01 00 30 e4 28 01
descriptor 4: 00 00 00 fe 00 4c 50 31 34 31 57 58 33 2d 54 4c 52 31
extensions: 00
checksum: d8
Manufacturer: LEN Model 4031 Serial Number 0
Made week 0 of 2008
EDID version: 1.3
Digital display
Maximum image size: 30 cm x 19 cm
Gamma: 220%
Check DPMS levels
DPMS levels: Standby Suspend Off
Supported color formats: RGB 4:4:4, YCrCb 4:2:2
First detailed timing is preferred timing
Established timings supported:
Standard timings supported:
Detailed timings
Hex of detail: 261b007d502016303020360030be10000018
Did detailed timing
Detailed mode (IN HEX): Clock 69500 KHz, 130 mm x be mm
0500 0530 0550 057d hborder 0
0320 0323 0329 0336 vborder 0
-hsync -vsync
Hex of detail: 8b16007d502016303020360030be10000018
Detailed mode (IN HEX): Clock 69500 KHz, 130 mm x be mm
0500 0530 0550 057d hborder 0
0320 0323 0329 0336 vborder 0
-hsync -vsync
Hex of detail: 0000000f00810a32810a2814010030e42801
Manufacturer-specified data, tag 15
Hex of detail: 000000fe004c503134315758332d544c5231
ASCII string: LP141WX3-TLR1
Checksum
Checksum: 0xd8 (valid)
WARNING: EDID block does NOT fully conform to EDID 1.3.
Missing name descriptor
Missing monitor ranges
bringing up panel at resolution 1280 x 800
Borders 0 x 0
Blank 125 x 22
Sync 32 x 6
Front porch 48 x 3
Spread spectrum clock
Single channel
Polarities 1, 1
Data M1=1214600, N1=8388608
Link frequency 270000 kHz
Link M1=134955, N1=524288
Pixel N=10, M1=14, M2=11, P1=1
Pixel clock 138857 kHz
waiting for panel powerup
panel powered up
</pre>
</div>
<div class="section">
<p>
Copyright © 2015 Francis Rowe <info@gluglug.org.uk><br/>
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.
A copy of the license can be found at <a href="../gfdl-1.3.txt">../gfdl-1.3.txt</a>
</p>
<p>
Updated versions of the license (when available) can be found at
<a href="https://www.gnu.org/licenses/licenses.html">https://www.gnu.org/licenses/licenses.html</a>
</p>
<p>
UNLESS OTHERWISE SEPARATELY UNDERTAKEN BY THE LICENSOR, TO THE
EXTENT POSSIBLE, THE LICENSOR OFFERS THE LICENSED MATERIAL AS-IS
AND AS-AVAILABLE, AND MAKES NO REPRESENTATIONS OR WARRANTIES OF
ANY KIND CONCERNING THE LICENSED MATERIAL, WHETHER EXPRESS,
IMPLIED, STATUTORY, OR OTHER. THIS INCLUDES, WITHOUT LIMITATION,
WARRANTIES OF TITLE, MERCHANTABILITY, FITNESS FOR A PARTICULAR
PURPOSE, NON-INFRINGEMENT, ABSENCE OF LATENT OR OTHER DEFECTS,
ACCURACY, OR THE PRESENCE OR ABSENCE OF ERRORS, WHETHER OR NOT
KNOWN OR DISCOVERABLE. WHERE DISCLAIMERS OF WARRANTIES ARE NOT
ALLOWED IN FULL OR IN PART, THIS DISCLAIMER MAY NOT APPLY TO YOU.
</p>
<p>
TO THE EXTENT POSSIBLE, IN NO EVENT WILL THE LICENSOR BE LIABLE
TO YOU ON ANY LEGAL THEORY (INCLUDING, WITHOUT LIMITATION,
NEGLIGENCE) OR OTHERWISE FOR ANY DIRECT, SPECIAL, INDIRECT,
INCIDENTAL, CONSEQUENTIAL, PUNITIVE, EXEMPLARY, OR OTHER LOSSES,
COSTS, EXPENSES, OR DAMAGES ARISING OUT OF THIS PUBLIC LICENSE OR
USE OF THE LICENSED MATERIAL, EVEN IF THE LICENSOR HAS BEEN
ADVISED OF THE POSSIBILITY OF SUCH LOSSES, COSTS, EXPENSES, OR
DAMAGES. WHERE A LIMITATION OF LIABILITY IS NOT ALLOWED IN FULL OR
IN PART, THIS LIMITATION MAY NOT APPLY TO YOU.
</p>
<p>
The disclaimer of warranties and limitation of liability provided
above shall be interpreted in a manner that, to the extent
possible, most closely approximates an absolute disclaimer and
waiver of all liability.
</p>
</div>
</body>
</html>
|
