| 1 | ====================================================
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| 2 | Testing suspend and resume support in device drivers
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| 3 | ====================================================
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| 4 |
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| 5 | (C) 2007 Rafael J. Wysocki <[email protected]>, GPL
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| 6 |
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| 7 | 1. Preparing the test system
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| 8 | ============================
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| 9 |
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| 10 | Unfortunately, to effectively test the support for the system-wide suspend and
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| 11 | resume transitions in a driver, it is necessary to suspend and resume a fully
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| 12 | functional system with this driver loaded. Moreover, that should be done
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| 13 | several times, preferably several times in a row, and separately for hibernation
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| 14 | (aka suspend to disk or STD) and suspend to RAM (STR), because each of these
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| 15 | cases involves slightly different operations and different interactions with
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| 16 | the machine's BIOS.
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| 17 |
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| 18 | Of course, for this purpose the test system has to be known to suspend and
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| 19 | resume without the driver being tested. Thus, if possible, you should first
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| 20 | resolve all suspend/resume-related problems in the test system before you start
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| 21 | testing the new driver. Please see Documentation/power/basic-pm-debugging.rst
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| 22 | for more information about the debugging of suspend/resume functionality.
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| 23 |
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| 24 | 2. Testing the driver
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| 25 | =====================
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| 26 |
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| 27 | Once you have resolved the suspend/resume-related problems with your test system
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| 28 | without the new driver, you are ready to test it:
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| 29 |
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| 30 | a) Build the driver as a module, load it and try the test modes of hibernation
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| 31 | (see: Documentation/power/basic-pm-debugging.rst, 1).
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| 32 |
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| 33 | b) Load the driver and attempt to hibernate in the "reboot", "shutdown" and
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| 34 | "platform" modes (see: Documentation/power/basic-pm-debugging.rst, 1).
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| 35 |
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| 36 | c) Compile the driver directly into the kernel and try the test modes of
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| 37 | hibernation.
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| 38 |
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| 39 | d) Attempt to hibernate with the driver compiled directly into the kernel
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| 40 | in the "reboot", "shutdown" and "platform" modes.
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| 41 |
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| 42 | e) Try the test modes of suspend (see:
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| 43 | Documentation/power/basic-pm-debugging.rst, 2). [As far as the STR tests are
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| 44 | concerned, it should not matter whether or not the driver is built as a
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| 45 | module.]
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| 46 |
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| 47 | f) Attempt to suspend to RAM using the s2ram tool with the driver loaded
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| 48 | (see: Documentation/power/basic-pm-debugging.rst, 2).
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| 49 |
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| 50 | Each of the above tests should be repeated several times and the STD tests
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| 51 | should be mixed with the STR tests. If any of them fails, the driver cannot be
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| 52 | regarded as suspend/resume-safe.
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