Re: [gentoo-user] radeon screen resolution

john <jdm@××××××××××××.uk> wrote:

> On Mon, 28 Dec 2015 13:41:57 +0000
> Mick <michaelkintzios@×××××.com> wrote:
>
> > On Monday 28 Dec 2015 09:11:10 john wrote:
> > > Hello,
> > >
> > > I have installed Gentoo on to another partition in order to use
> > > radeon drivers for desktop instead of fglrx.
> > >
> > > When I start my resolution is very small (1280x600) and only uses
> > > half the screen. My max resolution is 1920*1080 so I have a big
> > > black border around my screen. I can startx which works but cannot
> > > change the resolution to anything bigger. GRUB splash uses full
> > > screen but when the kernel loads it switches to small resolution.
> > >
> > > The only thing I can think of which is causing this issue is UEFI.
> > > In my other set (fglrx) up I have simple framebuffer enabled which
> > > works when I set up resolution in grub default.
> > >
> > > Strangely enough when I start system rescue cd in UEFI mode I get
> > > the same problem with small resolution but not if I do not boot in
> > > UEFI mode.
> >
> > Hmm ... I don't get such problems here on 3 PCs running different
> > amd/radeon cards and all with radeon drivers.
> >
> > You haven't said which card you're running.  If it is a very recent
> > model the radeon drivers may not have caught up with it yet?
> >
> > If you need to compare kernel settings let me know, although there
> > are wiki pages that are quite detailed on this topic.
> >
> >
> > > Anyone come across this or got this to work properly with
> > > radeon/UEFI?
> > >
> > > Moral, don't use UEFI I guess but that's the future???????!!!!!!
> > >
> > > John
> >
> > On PC boots in UEFI (directly boots the efi binary, no boot
> > managers) and it has no such problems on 2 x 1920*1080 monitors.
> >
>
> Hmm,
> thanks, I have now tried an old monitor and its screen
> resolution was good (ie 1920x1080) so I think it's the monitor.
> I have a R9 280 radeon card which is pretty new but the monitor is
> very new (display port only, acer xb240h model) so I guess it's
> something do do with that, perhaps EDID but not really sure. The
> whole graphics stack is pretty bemusing and I would love to make
> sense of it all.

Several months ago I was thinking about buying a LG monitor with 
Cinema4k (4096x2160) resolution. The monitor that I received had some
firmware bugs. One bug was that the monitor shows a broken (somewhat
incomplete) EDID block. So it was not possible to use the full 
resolution with the radeon driver but only UHD resolution (3840x2160).

I read somewhere that this monitor maybe would run fine with the fglrx 
driver. But because I don't like proprietary software and because the 
monitor also had some other bugs and IMHO also a poor picture quality, 
I decided to sent it back. 

There is a kernel option DRM_LOAD_EDID_FIRMWARE. It allows you to 
specify an EDID data set instead of probing for it. If your problem
is caused by broken EDID data, this option maybe will help you to run
the monitor at its full resolution.

--
Regards
wabe