| 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: Documentation/power/basic-pm-debugging.txt, 1). | |
| b) Load the driver and attempt to hibernate in the "reboot", "shutdown" and | |
| "platform" modes (see: Documentation/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: Documentation/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: Documentation/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. |