Bug 107161

Summary:	blank screen on Aluminum iMac, Radeon HD 6750M
Product:	Drivers	Reporter:	Sean Maguire (s_maguire)
Component:	Console/Framebuffers	Assignee:	James Simmons (jsimmons)
Status:	RESOLVED CODE_FIX
Severity:	normal
Priority:	P1
Hardware:	Intel
OS:	Linux
Kernel Version:	4.2.4	Subsystem:
Regression:	No	Bisected commit-id:

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.