/usr/bin/decode-edid is in i2c-tools 3.1.2-3.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
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 | #!/usr/bin/perl -w
#
# Copyright (C) 2003-2008 Jean Delvare <jdelvare@suse.de>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
# MA 02110-1301 USA.
#
# EEPROM data decoding for EDID. EDID (Extended Display Identification
# Data) is a VESA standard which allows storing (on manufacturer's side)
# and retrieving (on user's side) of configuration information about
# displays, such as manufacturer, serial number, physical dimensions and
# allowed horizontal and vertical refresh rates.
#
# Using the eeprom kernel driver, you have two possibilities to
# make use of these data:
# 1* The ddcmon script.
# 2* This script.
# Both solutions will return a different kind of information. The first
# method will report user-interesting information, such as the model number
# or the year of manufacturing. The second method will report video-card-
# interesting information, such as video modes and refresh rates.
#
# Note that this script does almost nothing by itself. It simply converts
# what it finds in /proc to binary data to feed the parse-edid program.
# The parse-edid program was written by John Fremlin and is available at
# the following address:
# http://john.fremlin.de/programs/linux/read-edid/
use strict;
use Fcntl qw(:DEFAULT :seek);
use vars qw($bus $address);
use constant PROCFS => 1;
use constant SYSFS => 2;
# parse-edid will typically be installed in /usr/sbin or /usr/local/sbin
# even though regular users can run it
$ENV{PATH} .= ':/usr/local/sbin'
if $ENV{PATH} !~ m,(^|:)/usr/local/sbin/?(:|$),
&& -x '/usr/local/sbin/parse-edid';
$ENV{PATH} .= ':/usr/sbin'
if $ENV{PATH} !~ m,(^|:)/usr/sbin/?(:|$),
&& -x '/usr/sbin/parse-edid';
sub edid_valid_procfs
{
my ($bus, $addr) = @_;
open EEDATA, "/proc/sys/dev/sensors/eeprom-i2c-$bus-$addr/00";
my $line = <EEDATA>;
close EEDATA;
return 1
if $line =~ m/^0 255 255 255 255 255 255 0 /;
return 0;
}
# Only used for sysfs
sub rawread
{
my ($filename, $length, $offset) = @_;
my $bytes = '';
sysopen(FH, $filename, O_RDONLY)
or die "Can't open $filename";
if ($offset)
{
sysseek(FH, $offset, SEEK_SET)
or die "Can't seek in $filename";
}
$offset = 0;
while ($length)
{
my $r = sysread(FH, $bytes, $length, $offset);
die "Can't read $filename"
unless defined($r);
die "Unexpected EOF in $filename"
unless $r;
$offset += $r;
$length -= $r;
}
close(FH);
return $bytes;
}
sub edid_valid_sysfs
{
my ($bus, $addr) = @_;
my $bytes = rawread("/sys/bus/i2c/devices/$bus-00$addr/eeprom", 8, 0);
return 1
if $bytes eq "\x00\xFF\xFF\xFF\xFF\xFF\xFF\x00";
return 0;
}
sub bus_detect
{
my $max = shift;
for (my $i=0; $i<$max; $i++)
{
if (-r "/proc/sys/dev/sensors/eeprom-i2c-$i-50/00")
{
if (edid_valid_procfs($i, '50'))
{
print STDERR
"decode-edid: using bus $i (autodetected)\n";
return $i;
}
}
elsif (-r "/sys/bus/i2c/devices/$i-0050/eeprom")
{
if (edid_valid_sysfs($i, '50'))
{
print STDERR
"decode-edid: using bus $i (autodetected)\n";
return $i;
}
}
}
return; # default
}
sub edid_decode
{
my ($bus, $addr, $mode) = @_;
# Make sure it is an EDID EEPROM.
unless (($mode == PROCFS && edid_valid_procfs ($bus, $addr))
|| ($mode == SYSFS && edid_valid_sysfs ($bus, $addr)))
{
print STDERR
"decode-edid: not an EDID EEPROM at $bus-$addr\n";
return;
}
$SIG{__WARN__} = sub { };
open PIPE, "| parse-edid"
or die "Can't open parse-edid. Please install read-edid.\n";
delete $SIG{__WARN__};
binmode PIPE;
if ($mode == PROCFS)
{
for (my $i=0; $i<=0x70; $i+=0x10)
{
my $file = sprintf '%02x', $i;
my $output = '';
open EEDATA, "/proc/sys/dev/sensors/eeprom-i2c-$bus-$addr/$file"
or die "Can't read /proc/sys/dev/sensors/eeprom-i2c-$bus-$addr/$file";
while(<EEDATA>)
{
foreach my $item (split)
{
$output .= pack "C", $item;
}
}
close EEDATA;
print PIPE $output;
}
}
elsif ($mode == SYSFS)
{
print PIPE rawread("/sys/bus/i2c/devices/$bus-00$address/eeprom", 128, 0);
}
close PIPE;
}
# Get the address. Default to 0x50 if not given.
$address = $ARGV[1] || 0x50;
# Convert to decimal, whatever the value.
$address = oct $address if $address =~ m/^0/;
# Convert to an hexadecimal string.
$address = sprintf '%02x', $address;
# Get the bus. Try to autodetect if not given.
$bus = $ARGV[0] if defined $ARGV[0];
$bus = bus_detect(8) unless defined $bus;
if(defined $bus)
{
print STDERR
"decode-edid: decode-edid version 1.1\n";
if (-r "/proc/sys/dev/sensors/eeprom-i2c-$bus-$address")
{
edid_decode ($bus, $address, PROCFS);
exit 0;
}
elsif (-r "/sys/bus/i2c/devices/$bus-00$address")
{
edid_decode ($bus, $address, SYSFS);
exit 0;
}
}
print STDERR
"EDID EEPROM not found. Please make sure that the eeprom module is loaded.\n";
print STDERR
"Maybe your EDID EEPROM is on another bus. Try \"decode-edid ".($bus+1)."\".\n"
if defined $bus;
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