gddccontrol and Sony SDM-HS94P problems

The Sony SDM-HS94P is a 1280x1024 19" monitor from back in 2004.

sudo get-edid | parse-edid
This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
No EDID on bus 0
No EDID on bus 2
No EDID on bus 4
No EDID on bus 5
No EDID on bus 6
2 potential busses found: 1 3
Will scan through until the first EDID is found.
Pass a bus number as an option to this program to go only for that one.
128-byte EDID successfully retrieved from i2c bus 1
Looks like i2c was successful. Have a good day.
Checksum Correct

Section "Monitor"
Identifier "SDM-HS94P"
ModelName "SDM-HS94P"
VendorName "SNY"
# Monitor Manufactured week 44 of 2004
# EDID version 1.3
# Analog Display
DisplaySize 380 300
Gamma 2.20
Option "DPMS" "true"
Horizsync 28-81
VertRefresh 48-75
# Maximum pixel clock is 140MHz
#Not giving standard mode: 1280x1024, 60Hz
#Not giving standard mode: 1280x960, 60Hz
Modeline "Mode 0" 108.00 1280 1328 1440 1688 1024 1025 1028 1066 +hsync +vsync
EndSection


asking for a ddccontrol probe gives me:


sudo ddccontrol -c -d dev:/dev/i2c-1
ddccontrol version 0.4.2
Copyright 2004-2005 Oleg I. Vdovikin (oleg@cs.msu.su)
Copyright 2004-2006 Nicolas Boichat (nicolas@boichat.ch)
This program comes with ABSOLUTELY NO WARRANTY.
You may redistribute copies of this program under the terms of the GNU General Public License.

Reading EDID and initializing DDC/CI at bus dev:/dev/i2c-1...
Invalid response, first byte is 0x51, should be 0x6e
0000: 51 83 f3 00 00 4f 14 da f9 7d eb fe 67 54 f9 21 | Q....O...}..gT.!
0010: 3a b1 fc d5 fc 47 c4 6a 2e ff 90 2c 92 10 6b dc | :....G.j...,..k.
0020: 06 39 af 6c 97 c5 ef f3 e8 9a 6e 12 f8 d7 49 e3 | .9.l......n...I.
0030: 04 5a 16 d6 d7 7e 3e 2c f6 1b 83 48 73 ff 7f b3 | .Z...~>,...Hs...
0040: 70 49 af | pI.
Invalid response, first byte is 0x51, should be 0x6e
0000: 51 83 f3 00 00 4f 14 da f9 7d eb fe 67 54 f9 21 | Q....O...}..gT.!
0010: 3a b1 fc d5 fc 47 c4 6a 2e ff 90 2c 92 10 6b dc | :....G.j...,..k.
0020: 06 39 af 6c 97 c5 ef f3 e8 9a 6e 12 f8 d7 49 e3 | .9.l......n...I.
0030: 04 5a 16 d6 d7 7e 3e 2c f6 1b 83 48 73 ff 7f b3 | .Z...~>,...Hs...
0040: 70 49 af | pI.
Invalid response, first byte is 0x51, should be 0x6e
0000: 51 83 f3 00 00 4f 14 da f9 7d eb fe 67 54 f9 21 | Q....O...}..gT.!
0010: 3a b1 fc d5 fc 47 c4 6a 2e ff 90 2c 92 10 6b dc | :....G.j...,..k.
0020: 06 39 af 6c 97 c5 ef f3 e8 9a 6e 12 f8 d7 49 e3 | .9.l......n...I.
0030: 04 5a 16 d6 d7 7e 3e 2c f6 1b 83 48 73 ff 7f b3 | .Z...~>,...Hs...
0040: 70 49 af | pI.
I/O warning : failed to load external entity "/usr/share/ddccontrol-db/monitor/SNY1B90.xml"
Document not parsed successfully.

EDID readings:
Plug and Play ID: SNY1B90 [VESA standard monitor]
Input type: Analog
=============================== WARNING ===============================
There is no support for your monitor in the database, but ddccontrol is
using a basic generic profile. Many controls will not be supported, and
some controls may not work as expected.
Please update ddccontrol-db, or, if you are already using the latest
version, please send the output of the following command to
ddccontrol-users@lists.sourceforge.net:

LANG= LC_ALL= ddccontrol -p -c -d

Thank you.
=============================== WARNING ===============================

Capabilities:
Invalid response, first byte is 0x51, should be 0x6e
0000: 51 83 f3 00 00 4f 14 da f9 7d eb fe 67 54 f9 21 | Q....O...}..gT.!
0010: 3a b1 fc d5 fc 47 c4 6a 2e ff 90 2c 92 10 6b dc | :....G.j...,..k.
0020: 06 39 af 6c 97 c5 ef f3 e8 9a 6e 12 f8 d7 49 e3 | .9.l......n...I.
0030: 04 5a 16 d6 d7 7e 3e 2c f6 1b 83 48 73 ff 7f b3 | .Z...~>,...Hs...
0040: 70 49 af | pI.
Invalid response, first byte is 0x51, should be 0x6e
0000: 51 83 f3 00 00 4f 14 da f9 7d eb fe 67 54 f9 21 | Q....O...}..gT.!
0010: 3a b1 fc d5 fc 47 c4 6a 2e ff 90 2c 92 10 6b dc | :....G.j...,..k.
0020: 06 39 af 6c 97 c5 ef f3 e8 9a 6e 12 f8 d7 49 e3 | .9.l......n...I.
0030: 04 5a 16 d6 d7 7e 3e 2c f6 1b 83 48 73 ff 7f b3 | .Z...~>,...Hs...
0040: 70 49 af | pI.
...
Capabilities read fail.

Controls (valid/current/max) [Description - Value name]:
Invalid response, first byte is 0x51, should be 0x6e
51 82 01 00 bc 4f 14 da f9 7d eb | Q....O...}.
Invalid response, first byte is 0x51, should be 0x6e
51 82 01 00 bc 4f 14 da f9 7d eb | Q....O...}.
...



So ddccontrol won't read the capabilities, gddccontrol displays a tab that only has the title of "zero", but I can do this manually to change the brightness and contrast:

(I'm specifying the specific device because I've got more than one monitor attached)

setting brightness to 60

sudo ddccontrol dev:/dev/i2c-1 -r 0x10 -w 60

setting contrast to 60

sudo ddccontrol dev:/dev/i2c-1 -r 0x12 -w 60


ddccontrol complains, but the monitor does respond. So at least I can make it work.

Writing 0x10, 0x3c(60)...
Invalid response, first byte is 0x51, should be 0x6e
51 82 01 10 ac 3c 94 da b9 7d eb | Q....<...}.
Invalid response, first byte is 0x51, should be 0x6e
51 82 01 10 ac 3c 94 da b9 7d eb | Q....<...}.
Invalid response, first byte is 0x51, should be 0x6e
51 82 01 10 ac 3c 94 da b9 7d eb | Q....<...}.