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# Lint as: python2, python3
# Copyright (c) 2014 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function
from functools import reduce
import codecs
import logging
import operator
import os
import six
from six.moves import map
from six.moves import range
import sys
# TODO: This is a quick workaround; some of our arm devices so far only
# support the HDMI EDIDs and the DP one at 1680x1050. A more proper
# solution is to build a database of supported resolutions and pixel
# clocks for each model and check if the EDID is in the supported list.
def is_edid_supported(host, width, height):
"""Check whether the EDID is supported by DUT
@param host: A CrosHost object.
@param width: The screen width
@param height: The screen height
@return: True if the check passes; False otherwise.
"""
# TODO: Support client test that the host is not a CrosHost.
platform = host.get_platform()
if platform in ('snow', 'spring', 'skate', 'peach_pi', 'veyron_jerry'):
if (width, height) in [(1280, 800), (1440, 900), (1600, 900),
(3840, 2160)]:
return False
if platform in ('kahlee', 'grunt'):
if (width, height) in [(3840, 2160)]:
return False
return True
class Edid(object):
"""Edid is an abstraction of EDID (Extended Display Identification Data).
It provides methods to get the properties, manipulate the structure,
import from a file, export to a file, etc.
"""
BLOCK_SIZE = 128
def __init__(self, data, skip_verify=False):
"""Construct an Edid.
@param data: A byte-array of EDID data.
@param skip_verify: True to skip the correctness check.
"""
if not Edid.verify(data) and not skip_verify:
raise ValueError('Not a valid EDID.')
self.data = data
@staticmethod
def verify(data):
"""Verify the correctness of EDID.
@param data: A byte-array of EDID data.
@return True if the EDID is correct; False otherwise.
"""
data_len = len(data)
if data_len % Edid.BLOCK_SIZE != 0:
logging.debug('EDID has an invalid length: %d', data_len)
return False
for start in range(0, data_len, Edid.BLOCK_SIZE):
# Each block (128-byte) has a checksum at the last byte.
if sys.version_info.major < 3:
checksum = reduce(operator.add,
list(map(ord, data[start:start+Edid.BLOCK_SIZE])))
else:
checksum = reduce(operator.add,
list(data[start:start+Edid.BLOCK_SIZE]))
if checksum % 256 != 0:
logging.debug('Wrong checksum in the block %d of EDID',
start // Edid.BLOCK_SIZE)
return False
return True
@classmethod
def from_file(cls, filename, skip_verify=False):
"""Construct an Edid from a file.
@param filename: A string of filename.
@param skip_verify: True to skip the correctness check.
"""
if not os.path.exists(filename):
raise ValueError('EDID file %r does not exist' % filename)
if filename.upper().endswith('.TXT'):
# Convert the EDID text format, returning from xrandr.
data = reduce(operator.add,
[codecs.decode(s.strip(), 'hex') for s in open(filename).readlines()])
else:
data = open(filename, 'rb').read()
return cls(data, skip_verify)
def to_file(self, filename):
"""Export the EDID to a file.
@param filename: A string of filename.
"""
with open(filename, 'w+') as f:
f.write(self.data)
# A constant object to represent no EDID.
NO_EDID = Edid('', skip_verify=True)
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