Issues using Radeon 5770 with DisplayPort

[joh22n]

Hi,

Since we have many people here with lots of knowledge about open-source drivers, maybe you can help me figure out an issue I'm having.

I got a new 2560x1440 monitor which supports 60 Hz at that resolution.

When I plug it into my graphics card (MSI 5770 Hawk) using DisplayPort, it only outputs 27 Hz which for obvious reasons is not usable.

xrandr shows that the monitor is running 2560x1440 at 60 Hz even though the monitor OSD shows 27 Hz and so do my eyes.

I tried the same monitor and cable with an old laptop which uses a first generation mobile i5 with integrated graphics (i5 430M) and that works beautifully, so I know the problem is not with the cable or monitor.

Are the current open drivers for my GPU even capable of outputting DisplayPort signal 1440p@60 Hz?

Thank you if you have any input!

UPDATE: I'm using stock Ubuntu 16.10 on both my computers.

[agd5f]

Does the 60 hz mode show up in xrandr?

[joh22n]

Yes, it does. It shows the monitor running 2560x1440 @ 59.9

And when I try "xrandr --rate 60" nothing changes.

[joh22n]

After testing my system with Windows 7, where it works fine on 2560x1440@60Hz, it seems to be clear that the bottleneck here are the drivers.

Now the biggest question is: is there any chance that the drivers for my 5770 will get support for DisplayPort 2560x1440@60Hz?

And the second question is: if I upgrade to a more modern GPU (something like Rx 200 series or up) will I get the full potential of my monitor without issues and out of the box?

[joh22n]

I would but HDMI only outputs maximum of 1920x1200 on my card according to specs. So, I haven't even bothered to try it.

[chithanh]

Is that happening on the console too? Before/after radeon takes over from VGA text more or simplefb? Did you try passing various values in the video=... kernel parameter?

[joh22n]

Is that happening on the console too? Before/after radeon takes over from VGA text more or simplefb? Did you try passing various values in the video=... kernel parameter?

I have not tried any of the advanced stuff because of ignorance on this subject. What kind of kernel parameter values could I test (and where would I set them)? And I'm not sure what "Before/after radeon takes over from VGA text more or simplefb?" means

[chithanh]

"Before/after radeon takes over from VGA text more or simplefb?" means

At first during boot, the display output will be controlled by the video BIOS or UEFI.
After the kernel loads, control will then be handed over to the driver.

My question is whether the 27 Hz issue happens already before the driver is in control over the graphics hardware.

[joh22n]

My question is whether the 27 Hz issue happens already before the driver is in control over the graphics hardware.

During the first stages of boot, monitor is running at 1152x720@75. As soon as I see Ubuntu loading screen it is switched to 2560x1440@27.

Setting kernel params (video=displayport:2560x1440@60) unfortunately did not change anything. It still runs at 27Hz even though xrandr shows it is running at 59.9Hz.

What is interesting is that given this supported resolution table, it runs lower resolutions with a lower refresh rate too.

DisplayPort-0 connected primary 2560x1440+0+0 (normal left inverted right x axis y axis) 597mm x 336mm
2560x1440 59.95*+ <---ACTUAL: 27Hz
2048x1080 60.00 24.00 <---ACTUAL: 40Hz
1920x1080 60.00 50.00 59.94
1920x1080i 60.00 50.00 59.94
1600x1200 60.00 <---ACTUAL: 40Hz
1280x1024 75.02 60.02
1152x864 75.00 <---ACTUAL: 75Hz


Thank you for the suggestions so far! It's great to get some help figuring this out!

[chithanh]

In that case, I think it is a problem with the radeon driver, and not something that can be fixed by switching to a different desktop environment.
Best report a bug at https://bugs.freedesktop.org/ about this.