Openmoko Bug #1841: white screen of death (WSOD) after resume
Openmoko Public Trac
bugs at docs.openmoko.org
Wed Aug 20 10:29:58 CEST 2008
#1841: white screen of death (WSOD) after resume
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Reporter: Rorschach | Owner: openmoko-devel
Type: defect | Status: new
Priority: highest | Milestone:
Component: unknown | Version: GTA02v5
Severity: critical | Resolution:
Keywords: wsod,resume | Blockedby:
Reproducible: always | Blocking:
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Comment(by andy):
It's hard to know what goes on for you at the moment. Here is some more
information about the issue.
The "white screen" thing is what we see with no video data coming OR the
LCM ASIC is unconfigured.
Glamo stops sending video data at suspend because we put it in very low
power state with no PLLs running. So, it's normal in early resume in fact
the LCM would show WSOD -- but the backlight is down at that time. And it
is also normal that after some short time first Glamo LCD controller is
resumed and then we reinitialize LCM ASIC. Then we bring up backlight so
you should never see any white display.
I have seen two behaviours that give WSOD despite the happy story above --
first is during resume, the Glamo's Reset pin is falsely activated by a
spike. Because we assume most Glamo registers survive suspend, this kills
us dead and the partial resume action we do on the registers does not
succeed to issue any video. So with that problem you get a sticky WSOD
until you reboot.
The second behaviour is that somehow resume is delayed by another driver
(?) sometimes, then the normal sequencing does happen but delayed. During
the delayed portion, the backlight came up normally but LCM ASIC reinit
did not happen, so you see the WSOD until that completes.
--
Ticket URL: <https://docs.openmoko.org/trac/ticket/1841#comment:5>
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