Arch Linux

tessem

Member

Registered: 2017-10-15

Posts: 2

2560x1080 resolution not work.

Hello, i see another topic with same subject, but it was tagget as solved when it is not true.

I have ATI Radeon 5650 GPU and linux distribs don't support proprietary driver already. But i faced of with the free driver doesn't support 2560x1080 resolution (for last 3 days i tried 5 distros and all have the same issue).

My be i have mistake and somebody can help my with this problem?

I already try cvt and xrandr. When i put

xrandr -output HDMI-0 --mode "2560x1080_60"

screen goes black and turn off.

V1del

Forum Moderator

Registered: 2012-10-16

Posts: 25,435

Re: 2560x1080 resolution not work.

This tells me that your card doesn't support that resolution for HDMI

tessem

Member

Registered: 2017-10-15

Posts: 2

Re: 2560x1080 resolution not work.

but i work in Offtopic and in linux with proprietary driver.

I resolve it by finding previous release of Chakra linux (2017.03) where catalyst driver enable in live CD and installed with system. There are some troubles after install. I resolve its, but i cant't update without take more troubles.

I think, it may work in free driver.

Last edited by tessem (2017-10-15 14:12:20)

seth

Member

From: Won't reply 2 private help req

Registered: 2012-09-03

Posts: 78,863

Re: 2560x1080 resolution not work.

You "work in offtopic"? ;-)

Pun aside, you can try
a) generating a modeline with reduced blanking (man cvt)
b) disable audio (in the radeon or amdgpu kernel module - whichever is in use, see eg. "modinfo amdgpu")

Notice that you'll be driving the output out of specs. Might work, but might be glitchy.

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Kabbone

Member

Registered: 2009-02-06

Posts: 32

Re: 2560x1080 resolution not work.

I also faced this problem already a while ago and did some more research today.
It seems like every card <HD7xxx doesn't support this resolution out of the box even if it was advertised at that time. My workaround until now is to set the frequency to 30 Hz for 2560x1080 and it will work fine.
After some trial and error today I recognized the maximum pixel clock rate is 165 Mhz and so you could get (at my monitor, differs a bit by the sync ranges) a frequency of 53.35 Hz.

If you use "cvt" for getting the sync parameters or in general the settings for your new mode, the first number after the string, in my case it tells 230.00, is the pixel clock rate, which can't be above the told 165. You could get higher refreshing rates if you can keep the values for the hsync and vsync low, for example by using the values of the edid, which were lower in my case than what cvt told me.

I also found a patch for the radeon driver to introduce a kernelparameter "hdmimhz" to be able to set the pixel clock rate higher. It seems like it does a kind of overclocking which also affects the voltage and could harm your hardware. It's also mentioned in the wiki and here and here are the discussions about the patch itself.
Unfortunately the patch needs to be adapted to the new kernel versions.

Last edited by Kabbone (2018-02-10 23:18:55)