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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 service_stopper
      9 from autotest_lib.client.cros.power import power_utils
     10 
     11 
     12 class hardware_Backlight(test.test):
     13     version = 1
     14 
     15     def initialize(self):
     16         """Perform necessary initialization prior to test run.
     17 
     18         Private Attributes:
     19           _backlight: power_utils.Backlight object
     20           _services: service_stopper.ServiceStopper object
     21         """
     22         super(hardware_Backlight, self).initialize()
     23         self._backlight = None
     24         # Stop powerd to avoid it adjusting backlight levels
     25         self._services = service_stopper.ServiceStopper(['powerd'])
     26         self._services.stop_services()
     27 
     28 
     29     def run_once(self):
     30         # optionally test keyboard backlight
     31         kblight = None
     32         kblight_errs = 0
     33         try:
     34             kblight = power_utils.KbdBacklight()
     35         except power_utils.KbdBacklightException as e:
     36             logging.info("Assuming no keyboard backlight due to %s", str(e))
     37 
     38         if kblight:
     39             init_percent = kblight.get_percent()
     40             try:
     41                 for i in xrange(100, -1, -1):
     42                     kblight.set_percent(i)
     43                     result = int(kblight.get_percent())
     44                     if i != result:
     45                         logging.error('keyboard backlight set %d != %d get',
     46                                       i, result)
     47                         kblight_errs += 1
     48             finally:
     49                 kblight.set_percent(init_percent)
     50 
     51         if kblight_errs:
     52             raise error.TestFail("%d errors testing keyboard backlight." % \
     53                                  kblight_errs)
     54 
     55         self._backlight = power_utils.Backlight()
     56         backlight_errs = 0
     57         backlight_max = self._backlight.get_max_level()
     58         for i in xrange(backlight_max + 1):
     59             self._backlight.set_level(i)
     60             result = self._backlight.get_level()
     61             if i != result:
     62                 # The kernel Documentation/ABI/stable/sysfs-class-backlight
     63                 # states that the requested brightness may not be the
     64                 # actual_brightness.
     65                 # Although not specified in the docs, let's allow the difference
     66                 # between requested brightness and actual_brightness percent be
     67                 # within a tolerance of 1 of each other.
     68                 actual_percent = self._backlight.get_percent()
     69                 expected_percent = float(i) / float(backlight_max) * 100.0
     70                 diff_percent = abs(actual_percent - expected_percent)
     71                 log_level_func = logging.warn
     72                 if diff_percent > 1:
     73                     backlight_errs += 1
     74                     log_level_func = logging.error
     75                     log_level_func('backlight expected vs. actual exceeds error'
     76                                    'tolerance')
     77                 log_level_func('backlight set %d != %d get', i, result)
     78                 log_level_func('backlight percent difference is %f%%',
     79                                diff_percent)
     80 
     81         if backlight_errs:
     82             raise error.TestFail("%d errors testing backlight." % \
     83                                  backlight_errs)
     84 
     85 
     86     def cleanup(self):
     87         if self._backlight:
     88             self._backlight.restore()
     89         self._services.restore_services()
     90         super(hardware_Backlight, self).cleanup()
     91