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      1 # Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
      2 # Use of this source code is governed by a BSD-style license that can be
      3 # found in the LICENSE file.
      4 import logging
      5 
      6 from autotest_lib.client.bin import test
      7 from autotest_lib.client.common_lib import error
      8 from autotest_lib.client.cros import power_utils, service_stopper
      9 
     10 
     11 class hardware_Backlight(test.test):
     12     version = 1
     13 
     14     def initialize(self):
     15         """Perform necessary initialization prior to test run.
     16 
     17         Private Attributes:
     18           _backlight: power_utils.Backlight object
     19           _services: service_stopper.ServiceStopper object
     20         """
     21         super(hardware_Backlight, self).initialize()
     22         self._backlight = None
     23         # Stop powerd to avoid it adjusting backlight levels
     24         self._services = service_stopper.ServiceStopper(['powerd'])
     25         self._services.stop_services()
     26 
     27 
     28     def run_once(self):
     29         # optionally test keyboard backlight
     30         kblight = None
     31         kblight_errs = 0
     32         try:
     33             kblight = power_utils.KbdBacklight()
     34         except power_utils.KbdBacklightException as e:
     35             logging.info("Assuming no keyboard backlight due to %s", str(e))
     36 
     37         if kblight:
     38             init_percent = kblight.get_percent()
     39             try:
     40                 for i in xrange(100, -1, -1):
     41                     kblight.set_percent(i)
     42                     result = int(kblight.get_percent())
     43                     if i != result:
     44                         logging.error('keyboard backlight set %d != %d get',
     45                                       i, result)
     46                         kblight_errs += 1
     47             finally:
     48                 kblight.set_percent(init_percent)
     49 
     50         if kblight_errs:
     51             raise error.TestFail("%d errors testing keyboard backlight." % \
     52                                  kblight_errs)
     53 
     54         self._backlight = power_utils.Backlight()
     55         backlight_errs = 0
     56         backlight_max = self._backlight.get_max_level()
     57         for i in xrange(backlight_max + 1):
     58             self._backlight.set_level(i)
     59             result = self._backlight.get_level()
     60             if i != result:
     61                 # The kernel Documentation/ABI/stable/sysfs-class-backlight
     62                 # states that the requested brightness may not be the
     63                 # actual_brightness.
     64                 # Although not specified in the docs, let's allow the difference
     65                 # between requested brightness and actual_brightness percent be
     66                 # within a tolerance of 1 of each other.
     67                 actual_percent = self._backlight.get_percent()
     68                 expected_percent = float(i) / float(backlight_max) * 100.0
     69                 diff_percent = abs(actual_percent - expected_percent)
     70                 log_level_func = logging.warn
     71                 if diff_percent > 1:
     72                     backlight_errs += 1
     73                     log_level_func = logging.error
     74                     log_level_func('backlight expected vs. actual exceeds error'
     75                                    'tolerance')
     76                 log_level_func('backlight set %d != %d get', i, result)
     77                 log_level_func('backlight percent difference is %f%%',
     78                                diff_percent)
     79 
     80         if backlight_errs:
     81             raise error.TestFail("%d errors testing backlight." % \
     82                                  backlight_errs)
     83 
     84 
     85     def cleanup(self):
     86         if self._backlight:
     87             self._backlight.restore()
     88         self._services.restore_services()
     89         super(hardware_Backlight, self).cleanup()
     90