Bug 107161 - blank screen on Aluminum iMac, Radeon HD 6750M
Summary: blank screen on Aluminum iMac, Radeon HD 6750M
Status: RESOLVED CODE_FIX
Alias: None
Product: Drivers
Classification: Unclassified
Component: Console/Framebuffers (show other bugs)
Hardware: Intel Linux
: P1 normal
Assignee: James Simmons
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2015-11-04 16:11 UTC by Sean Maguire
Modified: 2015-11-16 20:01 UTC (History)
0 users

See Also:
Kernel Version: 4.2.4
Subsystem:
Regression: No
Bisected commit-id:

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Description Sean Maguire 2015-11-04 16:11:00 UTC 
If the radeon module is loaded on my iMac with a 6570M graphics card, the monitor immediately goes blank.  A secondary monitor attached via the Thunderbird connector will still work.  I found this in version 4.2.4, and it still exists in versions 4.2.5 and 4.3.0.  Running X does not cause the screen to display content.  There are no errors reported by the kernel or the X server when this occurs.

If I back out commit 5a633828b4b2bef343826afcb0a70770c4911c55 "drm/radeon: Restore LCD backlight level on resume (>= R5xx)", then the screen displays as usual both in console and X mode.
Comment 1 Sean Maguire 2015-11-16 20:01:02 UTC 
Issue is resolved in 4.2.6.
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