[Bug 561802] Re: [i915] blank screen on Latitude E6410 (NOT E6510)

[Don Thompson]

I have been suffering this bug for some time as I've attempted to build
my E6410 with Ubuntu & have spun up various iterations of recent
releases  (10.04, 10.10 beta & now 10.10 release). My most recent
attempt to get this E6410 (i5 with Intel gfx) working has resulted in an
interesting find & repeatable workaround.

Ubuntu 10.10/AMD64 desktop
Linux  2.6.36-1-generic #7-Ubuntu SMP Thu Oct 21 20:36:01 UTC 2010 x86_64 GNU/Linux
Latest Intel drivers from: https://launchpad.net/~glasen/+archive/intel-driver

With external LCD monitor connected all comes up fine: images on
internal panel & external monitor; I can switch between mirrored or
extended display modes. If the external monitor is deselected/turned off
in the System->Monitors applet all is OK (& through a cold reboot). If
the external monitor is powered off the E6410 internal display functions
as expected including through a reboot/cold start. Conclusion:
everything is fine with external monitor connected whether it's powered
or not.

External monitor disconnected - E6410 boots to blank screen. Conclusion:
the internal panel is affected by the state of an input on the VGA port.
VGA port has only three inputs - optional monitor ID bit on pin 11,
serial data line on pin 12 and serial clock line on pin 15.

After checking 15pin hi-density D-SUB VGA port pinouts & tying the few
inputs to gnd or 5V I prove that pin 12 (serial data in) pulled high to
+5V allows my E6410 to boot with a functioning internal panel. So I've
now got an Ubuntu laptop that needs a hardware dongle (15pin D-SUB
connector with pin12/SDA pulled to pin 9/+5V).

Next step is to get a DisplayPort cable & check out if the standard
connector DisplayPort socket works.

I hope this helps direct some debug to the right resolution.

-- 
[i915] blank screen on Latitude E6410 (NOT E6510)
https://bugs.launchpad.net/bugs/561802
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