Problems with AMD screen resolution
Hello people. I'm having problems with the screen resolution of of my computer with started since I started using Trisquel 7 (Trisquel 6 worked fine). I have a 1366x768 monitor, but I can only use a 1024x768 resolution. I can't figure out with driver is being used in my computer (the ways I found on internet didn't worked). I have read somewhere in the forum about activating KMS, but I couldn't figure out how to do it. I used a net-install .iso and installed only the packages I use. My video board is a AMD HD6310.
Thanks for the atention.
Can you post somewhere your /var/log/Xorg.0.log ?
[ 29.581] (EE) Screen 0 deleted because of no matching config section.
[ 29.581] (II) UnloadModule: "radeon"
Xorg did not manage to make the "radeon" driver work and use the generic "vesa" driver instead.
If you have an Intel processor (with a graphical chipset) you should remove the video card (and get much better performance for less energy consumption).
If not and if you card model is very recent, you could try to the latest 3.16 kernel from jxself repository: http://jxself.org/linux-libre/
I had the same issue on someone else's computer but never got to fix it. For now it has Trisquel 6 without LTS enablement Xorg.
Try un-blacklisting the radeon kernel module in /etc/modprobe.d/disable-radeon.conf (comment out the line). But I don't think it will work for your graphics card because it's too new and probably requires the nonfree microcode for KMS (I had that issue)
I didn't try further, but you could try compiling a version of libdrm without radeon KMS support.
This is true: Newer AMD stuff won't work right without their blobs. This could cause the userland radeon driver to fail and give up, and then Trisquel would probably fallback to vesa. I hope that this isn't your case though.
I installed the 3.16 kernel and then only diference it had was my status bar showing my memory use in -67%(!). During boot it showed a error saying it was unable to start KMS because it was disabled by the bios (and I wans't able to find any information about this). My video is integrated with my CPU (a E-350), so it is not possible to remove it (or change it (my motherboard don't have pci slots)).
I just changed back to the 3.13 kernel, for now i think i will just use Vesa (it is not like the end of the world this).
Anyway, thanks for the help.
Maybe if you monkey around with your xorg.conf you might get the correct reso on vesa. I'm sorry but that's about as exact instructions I can give you, it's a bit of a black art...
Did you try un-blacklisting radeon? If that didn't work, blacklist it and compile libdrm without Radeon KMS.
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I ran into basically the same issue only with a older Nvidia card. I tried to fix it for a while but didn't get any further. I'm back on Trisquel 6 for now. Other than that 7 worked well for me.