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Message-ID: <20061124085900.GA5081@elf.ucw.cz> Date: Fri, 24 Nov 2006 09:59:00 +0100 From: Pavel Machek <pavel@....cz> To: Andrew Morton <akpm@...l.org>, kernel list <linux-kernel@...r.kernel.org>, "Rafael J. Wysocki" <rjw@...k.pl>, Linus Torvalds <torvalds@...l.org> Subject: s2ram debugging documentation Linus posted quite nice TRACE_RESUME how-to, and I think it is too nice to be hidden in archives of mailing list, so I turned it into Documentation piece. Signed-off-by: Pavel Machek <pavel@...e.cz> Add linus' how-to-get s2ram to work. --- commit 10ef1d7d246e5d041eeb076f045dd21167311324 tree a5deed96319360e4e1f4982d4a6574f23a4dfe23 parent b6be65f0eb2ba9a7d2c8cef7a7af9ae481fe3ec9 author Pavel <pavel@....ucw.cz> Fri, 24 Nov 2006 09:57:12 +0100 committer Pavel <pavel@....ucw.cz> Fri, 24 Nov 2006 09:57:12 +0100 Documentation/power/s2ram.txt | 56 +++++++++++++++++++++++++++++++++++++++++ 1 files changed, 56 insertions(+), 0 deletions(-) diff --git a/Documentation/power/s2ram.txt b/Documentation/power/s2ram.txt new file mode 100644 index 0000000..50dce18 --- /dev/null +++ b/Documentation/power/s2ram.txt @@ -0,0 +1,56 @@ + How to get s2ram working + ~~~~~~~~~~~~~~~~~~~~~~~~ + 2006 Linus Torvalds + 2006 Pavel Machek + +1) Check suspend.sf.net, program s2ram there has long whitelist of + "known ok" machines, along with tricks to use on each one. + +2) If that does not help, try reading tricks.txt and + video.txt. Perhaps problem is as simple as broken module, and + simple module unload can fix it. + +3) You can use Linus' TRACE_RESUME infrastructure, described below. + + Using TRACE_RESUME + ~~~~~~~~~~~~~~~~~~ + +I've been working at making the machines I have able to STR, and almost +always it's a driver that is buggy. Thank God for the suspend/resume +debugging - the thing that Chuck tried to disable. That's often the _only_ +way to debug these things, and it's actually pretty powerful (but +time-consuming - having to insert TRACE_RESUME() markers into the device +driver that doesn't resume and recompile and reboot). + +Anyway, the way to debug this for people who are interested (have a +machine that doesn't boot) is: + + - enable PM_DEBUG, and PM_TRACE + + - use a script like this: + + #!/bin/sh + sync + echo 1 > /sys/power/pm_trace + echo mem > /sys/power/state + + to suspend + + - if it doesn't come back up (which is usually the problem), reboot by + holding the power button down, and look at the dmesg output for things + like + + Magic number: 4:156:725 + hash matches drivers/base/power/resume.c:28 + hash matches device 0000:01:00.0 + + which means that the last trace event was just before trying to resume + device 0000:01:00.0. Then figure out what driver is controlling that + device (lspci and /sys/devices/pci* is your friend), and see if you can + fix it, disable it, or trace into its resume function. + +For example, the above happens to be the VGA device on my EVO, which I +used to run with "radeonfb" (it's an ATI Radeon mobility). It turns out +that "radeonfb" simply cannot resume that device - it tries to set the +PLL's, and it just _hangs_. Using the regular VGA console and letting X +resume it instead works fine. -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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