trying to switch from nVidia.. what works on ATI and what doesn't?

[rohcQaH]

Hi,

I'm currently using a GeForce 7600GT in dual-screen-mode, but need something more powerful when GTA IV is released. The computer is mainly running linux though.

Since newer nVidia-cards are way too power-hungry and have poor 2D-acceleration I was thinking about getting a HD 4670. I'm aware I'll have to use the proprietary drivers for quite a while, but I'm hoping the OS drivers will mature during the next 2-3 years the gfx card is supposed to last.

I won't switch to ATI if I have to suffer regressions and I don't want to spend the money before knowing what'll work, but neither driver readme, nor google nor forum search led me to the answers I needed.

On to the issues at hand:

• I use two monitors in twinview mode (no server-side Xinerama) with a simple composition manager (kwin3). Any problems/restrictions in that mode on ATI? I require full acceleration across both monitors (2D and 3D).
• I often start the computer without powering on the monitors, so the driver won't get any EDID on initialisation. The nvidia-drivers allowed me to dump the EDID to a file and override it via
  Option "CustomEDID" "DFP-0:/etc/X11/245b.edid; DFP-1:/etc/X11/214t.edid"
  Is there a similar option for the fglrx drivers?
• I like using two simultaneous X servers. Work stuff is on :0 (VT7), fullscreen games will spawn their own X server on :1 (VT8). Will that configuration work flawlessly using the latest drivers? The point of spawning a new X server is to prevent disruption of my "work" X server, the whole exercise is pretty pointless if it leads to lockups or X crashes.
• anything else not working that should be?

thanks in advance for any advice you can offer. Seeing a gfx card that offers 2-3 times the performance of mine at less than 60W makes me giddy with joy, but I'd like to prevent any disappointment

[FunkyRider]

My 2 cents:

Get an nvidia (9600GT) and check back to ATI after a year, period.

[Linuxhippy]

Currently 2D accaleration for HD2/3/4 chips (R600+) is pretty poor to non-existent, whereas NVidia is currently working hard on getting that things right.
177.80 already did improve *many* things

- Clemens

[psycho_driver]

My 2 cents:

Get an nvidia (9600GT) and check back to ATI after a year, period.

All the information you need in the first reply. 'Upgrading' to an ATi card will be a big disappointment for you, at least in linux.

[liels]

XV output has major tearing; mythtv is hopeless until that is fixed.

[TechMage89]

I'd like to give more complete information on the status of ati on Linux.

Using the closed source (fglrx) drivers, everything works, but there are some bugs with 2d performance (like sometimes crop up with nvidia.) Also, unlike nvidia, 3d doesn't work very well with compositing, because they haven't integrated dri2 yet (nvidia uses a proprietary workaround.) There is still tearing, as well (because that's also something that dri2 will fix). The 3d performance of the ati cards is about the same on Windows and Linux. Also, AMD has been working on exposing UVD2 functionality in fglrx with an api called "XvBA" for full video decode acceleration. (If they get this fully working, AMD will have the only drivers that support this.)

The open-source drivers presently only support modesetting on r600+, and initial 2d/3d acceleration for these cards is coming "real soon now" according to bridgman. The initial 3d support will likely be only version 1.3, but it seems quite possible that we could have 2.1 or even 3.0 by sometime early next year. Also, dri2, gem, and kernel modesetting support is currently being being developed and tested, so it should make it into ati drivers quickly.

In short, if you want something that works well right now, nvidia's closed-source drivers are marginally better (no tearing, slightly more stable). However, in the long term, ati will likely have the best open-source drivers (nouveau has to reverse engineer everything, leaving them always behind. Bridgman has stated that AMD's aim is to have documentation and/or open-source driver code available on a card's release in the future.) Nvidia's drivers are starting to fall behind, lacking kernel modesetting and other modern features.

[tmpdir]

Saying that ATI drivers will be beter in the near future is premature at least.

I like the way ATI is working these days, but Nvidea's drivers are currently not "a little better" but a "whole lot better". Just do some internet searching yourself and you'll see the ammount and degree of trouble with ati drivers are currently much higher.

That said I have high hopes for the upcoming ATI driver (as I had with the versions from 8.4 to 8.10) and still considering to buy ati brands for my new htpc. But mean while time didn't stand still and my previous choices are outdated and I need to look arround again, which I don't mind...

[grigi]

On to the issues at hand:

• I use two monitors in twinview mode (no server-side Xinerama) with a simple composition manager (kwin3). Any problems/restrictions in that mode on ATI? I require full acceleration across both monitors (2D and 3D).

I'm using fglrx on my notebook (X1600), and dual-screen is perfect. The issue moest people have is that you should NOT use xinerama, you should use the aticonfig utility to set up twinview. I can dynamically turn the external monitor on/off by running 'aticonfig --enable-monitor=auto`, which will detect the monitors and re-adjust on the fly.

• I often start the computer without powering on the monitors, so the driver won't get any EDID on initialisation. The nvidia-drivers allowed me to dump the EDID to a file and override it via
  Option "CustomEDID" "DFP-0:/etc/X11/245b.edid; DFP-1:/etc/X11/214t.edid"
  Is there a similar option for the fglrx drivers?

I don't know, what I do at my home pc (4850), is configure the resolution of the monitor the old-fashioned way (specifying the resolution in xorg.conf)

• I like using two simultaneous X servers. Work stuff is on :0 (VT7), fullscreen games will spawn their own X server on :1 (VT8). Will that configuration work flawlessly using the latest drivers? The point of spawning a new X server is to prevent disruption of my "work" X server, the whole exercise is pretty pointless if it leads to lockups or X crashes.

No. fglrx can only run one server.

• anything else not working that should be?

I find that since most linux apps/games are only ever tested on NVidia (because of some percieved superiority of nvidia) that ATi divers are essentially forced to play catch-up. Some games I tried justs disables some features if it doesn't detect a Nvidia card. Wrongfully so, those devs should be shot.

Other issues is that generally you should use 'opengl' out as the video renderer, and not Xv. Xv does work, but I found that opengl just works better.

As other people mentioned there is flickering/tearing when rendering an embedded overlay when using any composite desktop. This is worse when using Xv. I have found that kde4's composite renderer has no flickering issues on my 4850 desktop. Tearing still happens when watching video, though.

The tearing/flickering issues are gone when not using a composite desktop.

The last issue is, it is a different driver, so the options on how to control it is different, keep that in mind. You would have to spend some time in tuning the drivers if you want to do special stuff. There is plenty of decent howto's out there, but on my 4850 I have yet to do any customization


What it does better than nvidia drivers:
Power-management works beautifully, and my and others ati-based notebook gets significantly better battery life in Linux than it does in Windows XP. Whereas all my colleagues with nvidia-based notebooks get significantly worse battery life in Linux than in XP.

[energyman]

things that work for me:
without compositing, xv is perfect. No flickering, ut2004, vegastrike 0.5 are fast. switching from vt to X and back works. logging out and back in via kdm works - if I log out vial ctrl-alt-backspace. Flash works

with compositing, xv is flickering like hell. Flash still works without flickering, ut2004 still fast. Manual window resizing slow, maximimising, minimizing is fast. Moving windows around is fast.

[rohcQaH]

Thank you for your replies.

I wasn't aware that 2D acceleration on the newer cards without dedicated 2D-hardware is a problem on ATI cards as well. Thank you for pointing that out, I'll probably need to stick to my trusty 7600 GT until that's resolved.

A gfx card is supposed to last a couple of years, so getting a (power-hungry) 9600GT and buying another card in a year is not an option. I'm also limited to a power-consumption of 60-70W, which rules out most nVidia-cards that are significantly faster than my 7600GT.
It's currently a decision between getting the HD 4670 and playing GTA IV (and everything else on higher details), or keeping the 7600GT for a while longer and wasting my time on other things.

Right now I'll wait, but there's at least a month until GTA IV is released and playable, probably two until the first patches are around.
I'll do some more googling then, and maybe I'll just bump the thread.