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