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#1 2020-01-25 04:31:20

MightyWatcher
Member
Registered: 2019-12-30
Posts: 10

Blurry screen when resolution increased with xrandr.

I would like to get 2560x1440 resolution using my Radeon 4290 IGP, which supports up to 2560x1600. I am using the xf86-video-ati driver.

Following the guide for adding undetected resolutions results in blurry/pixelated display, like the old resolution is being upscaled.

Not sure if related, but xrandr --listmonitors says I'm using HDMI, even though I'm connected to my monitor through DVI

$ xrandr --listmonitors
Monitors: 1
 0: +HDMI-0 1920/597x1080/336+0+0  HDMI-0

Please help!

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#2 2020-01-25 08:43:44

seth
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Registered: 2012-09-03
Posts: 49,992

Re: Blurry screen when resolution increased with xrandr.

Or downscaled. You get a blurry image if you'd eg. "xrandr --output HDMI-0 --scale 2x2" and that's not because of the output, but because you're crushing 3840x2160px into a FullHD scanout.

=> What's the actual monitor vendor and model you're dealing with here?

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#3 2020-01-25 09:07:35

MightyWatcher
Member
Registered: 2019-12-30
Posts: 10

Re: Blurry screen when resolution increased with xrandr.

I'm using an ASUS PB278Q.

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#4 2020-01-25 10:42:43

Ropid
Member
Registered: 2015-03-09
Posts: 1,069

Re: Blurry screen when resolution increased with xrandr.

Maybe for some reason the DVI connection you are using is actually "DVI-A" and not "DVI-D"? That "DVI-A" thing is basically an analog VGA connection, just in a DVI connector shape. Maybe that's why it thinks it's 1920x1080, because that's the limitation of a VGA connection on this Radeon 4290 IGP?

Can you share more details? What is your motherboard? What are the video outputs it has? How do you connect your monitor exactly? Is it DVI on the motherboard side with a DVI-VGA adapter, and then VGA on the monitor side?

Last edited by Ropid (2020-01-25 10:44:53)

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#5 2020-01-25 12:20:59

MightyWatcher
Member
Registered: 2019-12-30
Posts: 10

Re: Blurry screen when resolution increased with xrandr.

I am using a Biostar TA890GXB. As it is an integrated graphics processor on the CPU, I am connected to my monitor through the motherboard rear I/O DVI port, which according to the data sheet is DVI-D, not DVI-A. No adapters.

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#6 2020-01-25 14:39:25

seth
Member
Registered: 2012-09-03
Posts: 49,992

Re: Blurry screen when resolution increased with xrandr.

Check the slots and plugs and compare them to https://en.wikipedia.org/wiki/Digital_V … _Types.svg - you need a dual link connection. Theoretically you could use a single link cable on dual link slots, but this would still be a single link connection (and limited to FullHD)

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#7 2020-01-25 14:43:37

MightyWatcher
Member
Registered: 2019-12-30
Posts: 10

Re: Blurry screen when resolution increased with xrandr.

This motherboard has a dual link DVI port (all pins are present). The cable I'm using is dual link and tests working on another computer with this monitor at 2560x1440.

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#8 2020-01-25 15:01:28

seth
Member
Registered: 2012-09-03
Posts: 49,992

Re: Blurry screen when resolution increased with xrandr.

'key.
Please post your xorg log (should contain  the acquired EDID) and the outputs of "xrandr -q" and "xrandr -q --verbose" after adding and selecting the desired resolution.

One unexpected thing might be a compositor (picom or from your window manager) failing to update the viewport on the randr event that changes the resolution (or being outright unable to do so because of eg. a 2048x2048 texture limit)

Last thing: drop xf86-video-ati to see how the modesetting driver behaves.

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#9 2020-01-26 05:14:36

MightyWatcher
Member
Registered: 2019-12-30
Posts: 10

Re: Blurry screen when resolution increased with xrandr.

Xorg log after changing resolutions.

Output of xrandr -q.

Output of xrandr -q --verbose

Tried disabling picom, same result.

Last, tried to use modesetting, by uninstalling xf86-video-ati and running startx, gives black screen. I don't know how to fix this now.

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#10 2020-01-26 09:08:53

seth
Member
Registered: 2012-09-03
Posts: 49,992

Re: Blurry screen when resolution increased with xrandr.

re-install xf86-video-ati but there's probably a file in /{etc,usr/share}/X11/xorg.conf.d/* that selects

[    12.511] (II) Applying OutputClass "Radeon" to /dev/dri/card0
[    12.511] 	loading driver: radeon

, and thus rules out the modesetting driver. Lose that configlet (move it to your $HOME in doubt)

---

Resolutions above FullHD are not dropped, but not probed at all (so it's not that the GPU says "I can't do this) and the output isn't scaled either. I assume the monitors OSD suggests that it's running at 2560x1440?

Wild guess: try to create a modeline with reduced blanking.

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#11 2020-01-26 11:19:39

Ropid
Member
Registered: 2015-03-09
Posts: 1,069

Re: Blurry screen when resolution increased with xrandr.

Can you try this modeline here and see what happens?

$ cvt -r 2560 1440 60
# 2560x1440 59.95 Hz (CVT 3.69M9-R) hsync: 88.79 kHz; pclk: 241.50 MHz
Modeline "2560x1440R"  241.50  2560 2608 2640 2720  1440 1443 1448 1481 +hsync -vsync

Or this one here:

$ cvt12 2560 1440 60 -b
# 2560x1440 @ 60.000 Hz Reduced Blank (CVT) field rate 60.000 Hz; hsync: 88.860 kHz; pclk: 234.59 MHz
Modeline "2560x1440_60.00_rb2"  234.59  2560 2568 2600 2640  1440 1467 1475 1481 +hsync -vsync

If you compare these two to the one you used, you'll see that the "pixel clock" value is much lower because the "reduced blank" version of the calculations were used. On the modeline you tried to use, it's 312.250 MHz, while on these ones here it's 241.5 MHz or 234.59 MHz. This might be important, perhaps the data does not fit into the connection's bandwidth without reduced blank.

The "cvt12" program I used to generate the second modeline is in the AUR.

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