Bug 47351

Summary: [KMS: Mobility Radeon HD 6620G] Blank screen on boot
Product: Drivers Reporter: Michael Walton (spesialstyrker)
Component: Video(DRI - non Intel)Assignee: drivers_video-dri
Status: RESOLVED DOCUMENTED    
Severity: normal CC: alan, alexdeucher, ka.nick
Priority: P1    
Hardware: All   
OS: Linux   
Kernel Version: 3.5.3 Subsystem:
Regression: No Bisected commit-id:
Attachments: lspci -vv output

Description Michael Walton 2012-09-10 20:12:03 UTC
Booting without nomodeset in the kernel parameters results in a blank screen using 3.5.3 kernel, and same behavior on mainline kernel version as well.
Comment 1 Alex Deucher 2012-09-10 20:19:08 UTC
Possibly a duplicate of bug 47321.  Do you have the firmware installed and accessible in your initrd?  Also possibly related:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=d8636a2717bb3da2a7ce2154bf08de90bb8c87b0
or:
http://lists.freedesktop.org/archives/dri-devel/2012-September/027545.html
Comment 2 Michael Walton 2012-09-10 20:26:09 UTC
Actually I didn't see when I looked before filing the report, but this looks like my exact situation including the suspend issues. Sorry for the duplicate report!

https://bugzilla.kernel.org/show_bug.cgi?id=46241
Comment 3 Michael Walton 2012-09-10 20:29:17 UTC
I don't know if it's the same as bug 47321 Mr. Deucher because the system will boot with KMS enabled, but the screen just stays blank.
Comment 4 Alex Deucher 2012-09-10 20:35:35 UTC
(In reply to comment #2)
> Actually I didn't see when I looked before filing the report, but this looks
> like my exact situation including the suspend issues. Sorry for the duplicate
> report!
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=46241

That bug is for a blank screen on resume not boot.  Do you only get a blank screen on resume, but not boot?  Also, is this a regression?  I.e., did previous kernels work?  If so, can you bisect?
Comment 5 Nick 2013-04-29 12:01:07 UTC
Created attachment 100251 [details]
lspci -vv output

I have the same behaviour on my HP 4545s laptop if I try to use discrete video card (HD7500/7600). I managed to get it work (more or less) on integrated 7240G, but I get blank screen having tried to switch to discrete video. Can I provide any additional information to help to resolve the issue?
Comment 6 Alex Deucher 2013-04-29 14:20:38 UTC
(In reply to comment #5)

> I have the same behaviour on my HP 4545s laptop if I try to use discrete
> video
> card (HD7500/7600). I managed to get it work (more or less) on integrated
> 7240G, but I get blank screen having tried to switch to discrete video. Can I
> provide any additional information to help to resolve the issue?

Most hybrid laptops are mux-less meaning there are no displays physically connected to the discrete GPU.  For display you have to use the integrated GPU.  The discrete GPU can only be used for offscreen rendering.  Do display that rendering, it has to be copied to the integrated GPU.  There is limited support for this in newer xservers (1.13.x and newer).
Comment 7 Nick 2013-04-30 11:39:28 UTC
Yes, I'm quite sure my laptop is mux-less, so I guess the card actually works but cannot output anything... 
I've 1.13.4 installed (and 1.14.1 is available in portage softmasked). Is there any chance I could make use of this?
Comment 8 Alex Deucher 2013-04-30 12:57:39 UTC
(In reply to comment #7)
> Yes, I'm quite sure my laptop is mux-less, so I guess the card actually works
> but cannot output anything... 
> I've 1.13.4 installed (and 1.14.1 is available in portage softmasked). Is
> there
> any chance I could make use of this?

You can use xrandr to configure it using the -setprovideroutputsource and -setprovideroffloadsink parameters
Comment 9 Nick 2013-04-30 13:18:22 UTC
Thank you!