|  | Testing suspend and resume support in device drivers | 
|  | (C) 2007 Rafael J. Wysocki <rjw@sisk.pl>, GPL | 
|  |  | 
|  | 1. Preparing the test system | 
|  |  | 
|  | Unfortunately, to effectively test the support for the system-wide suspend and | 
|  | resume transitions in a driver, it is necessary to suspend and resume a fully | 
|  | functional system with this driver loaded.  Moreover, that should be done | 
|  | several times, preferably several times in a row, and separately for hibernation | 
|  | (aka suspend to disk or STD) and suspend to RAM (STR), because each of these | 
|  | cases involves slightly different operations and different interactions with | 
|  | the machine's BIOS. | 
|  |  | 
|  | Of course, for this purpose the test system has to be known to suspend and | 
|  | resume without the driver being tested.  Thus, if possible, you should first | 
|  | resolve all suspend/resume-related problems in the test system before you start | 
|  | testing the new driver.  Please see Documentation/power/basic-pm-debugging.txt | 
|  | for more information about the debugging of suspend/resume functionality. | 
|  |  | 
|  | 2. Testing the driver | 
|  |  | 
|  | Once you have resolved the suspend/resume-related problems with your test system | 
|  | without the new driver, you are ready to test it: | 
|  |  | 
|  | a) Build the driver as a module, load it and try the test modes of hibernation | 
|  | (see: Documents/power/basic-pm-debugging.txt, 1). | 
|  |  | 
|  | b) Load the driver and attempt to hibernate in the "reboot", "shutdown" and | 
|  | "platform" modes (see: Documents/power/basic-pm-debugging.txt, 1). | 
|  |  | 
|  | c) Compile the driver directly into the kernel and try the test modes of | 
|  | hibernation. | 
|  |  | 
|  | d) Attempt to hibernate with the driver compiled directly into the kernel | 
|  | in the "reboot", "shutdown" and "platform" modes. | 
|  |  | 
|  | e) Try the test modes of suspend (see: Documents/power/basic-pm-debugging.txt, | 
|  | 2).  [As far as the STR tests are concerned, it should not matter whether or | 
|  | not the driver is built as a module.] | 
|  |  | 
|  | f) Attempt to suspend to RAM using the s2ram tool with the driver loaded | 
|  | (see: Documents/power/basic-pm-debugging.txt, 2). | 
|  |  | 
|  | Each of the above tests should be repeated several times and the STD tests | 
|  | should be mixed with the STR tests.  If any of them fails, the driver cannot be | 
|  | regarded as suspend/resume-safe. |