Bug 73911

Is this a regression?  Please attach your xorg log and dmesg output.

Created attachment 92587 [details]
dmesg

Created attachment 92588 [details]
Xorg.0.log

(In reply to comment #1)
> Is this a regression?  Please attach your xorg log and dmesg output.

No; I can't recall the lowest kernel and other components I used, but it's happened with every distro I've tried on this laptop (the oldest distro tried was Ubuntu 12.04.3).

It seems the color banding is only present with non-fullscreen applications and videos, but I'm not 100% certain. The desktop background on Xubuntu 13.10, the dashboard on Ubuntu's Unity, and Steam (both desktop and big picture) show the banding the worst though.

Created attachment 92590 [details]
example-1

Created attachment 92591 [details]
example-1

Created attachment 92592 [details]
example-2

Same problem here.

When using the open driver for my graphic card (Radeon HD 6520G, on APU A6-3400m) I get ugly gradients and color banding (see the attachment). Everything fine and smooth with Catalyst.

I want to stay with the open drivers, but this issue is driving me crazy.

I have tested with kernels 3.10, 3.11, 3.12 and 3.13. With and without DPM.

[img width=599 height=800]http://s29.postimg.org/b6sftnq07/IMG_20140202_100203.jpg[/img]

Are you only having problems with the built in display on the laptop?

Created attachment 93321 [details] [review]
testing patch

Does this kernel patch help?

Right now Im at the office, I will test with a external screen when I get home.

Im not experienced with patching the Kernel, I gonna do some reading so I can try the patch.

Hi I am having the same issue with Banding using the open source Radeon Driver. 
My laptop is an Acer Acpire 5560G with Radeon HD6520G + 7470M I have tryed a few different Distros and I get the same Banding problems at the moment I have Ubuntu-Gnome 14.04 2.13 kernel and Fedora 20 3.12 Kernel 

NOTE: I have noticed the Banding only happens on the built in Laptop Screen if I attach an external Monitor either VGA or HDMI the displays on those monitors are fine, no Banding. 
Running xwininfo shows my Depth is 24 bit I originally thought that may have been set to 15.

(In reply to comment #12)
> Hi I am having the same issue with Banding using the open source Radeon
> Driver. 
> My laptop is an Acer Acpire 5560G with Radeon HD6520G + 7470M I have tryed a
> few different Distros and I get the same Banding problems at the moment I
> have Ubuntu-Gnome 14.04 2.13 kernel and Fedora 20 3.12 Kernel 

Can you try the patch in comment 10?

(In reply to comment #13)
> (In reply to comment #12)
> Hi I am having the same issue with Banding using
> the open source Radeon
> Driver. 
> My laptop is an Acer Acpire 5560G with
> Radeon HD6520G + 7470M I have tryed a
> few different Distros and I get the
> same Banding problems at the moment I
> have Ubuntu-Gnome 14.04 2.13 kernel
> and Fedora 20 3.12 Kernel 

Can you try the patch in comment 10?

No problem Alex I will try the patch when I get home this afternoon and report back.

(In reply to comment #13)
> (In reply to comment #12)
> > Hi I am having the same issue with Banding using the open source Radeon
> > Driver. 
> > My laptop is an Acer Acpire 5560G with Radeon HD6520G + 7470M I have tryed a
> > few different Distros and I get the same Banding problems at the moment I
> > have Ubuntu-Gnome 14.04 2.13 kernel and Fedora 20 3.12 Kernel 
> 
> Can you try the patch in comment 10?

I applied the patch on Fedora20, no go I'm afraid I still have banding on the built in screen.

I'm experiencing the same problem with an AMD A10-4600M in an Asus N56DP laptop. I don't have an external screen to test at the moment, so can't be sure if it's evident there as well.

I tried the patch with both 3.13 and 3.14-rc4 (with some edits due to it not applying cleanly for the latter) and the patch actually causes a flickering black screen on boot, with some faint green line popping up periodically. Perhaps I applied the patch inproperly, though.

As far as the banding goes, the problem is particularly evident when running Steam and looking at the grey background, which is filled with multi-coloured banding.

I have a A8-6500 (kernel, mesa from git) and i too have banding in Steam and the xfce desktop if i set gradient background. 
But this doesnt show in gimp for example is i create a gradient.

I have the same problem on my laptop Samsung NP355V4C with 7660G and 7670M. I have tried 3.13 kernel on Kubuntu 14.04 x86-64 and Debian Wheezy x86-64 (with default debian kernel config from /boot), and this problem was observed in both distributions.

*** Bug 76884 has been marked as a duplicate of this bug. ***

Created attachment 96751 [details] [review]
testing patch

Does this patch help?

(In reply to comment #20)
> Created attachment 96751 [details] [review] [review]
> testing patch
> 
> Does this patch help?

unfortunately I can't test it as of now, I don't have enough disk space to compile the patched kernel. didn't know it would eat up my last 12GB.

(In reply to comment #20)
> Created attachment 96751 [details] [review] [review]
> testing patch
> 
> Does this patch help?

it doesn't look like it helps. same problem as before. my cursor has also disappeared, but that might be a problem of that I haven't worked with the kernel before at all.

My laptop with A8-4500m is also affected. With fglrx colors are fine, but I can see little amount of noise (dithering?). With open source drivers, there is no noise.

(In reply to comment #23)
> My laptop with A8-4500m is also affected. With fglrx colors are fine, but I
> can see little amount of noise (dithering?). With open source drivers, there
> is no noise.

the noise is definitely dithering, since dithering accomplishes colour blending using patterns similar to noise. it shouldn't be so noticeable in general use, but, trying to accomplish smooth gradients with only 1/4 of the colour values per channel is difficult.

haven't been able to sort this out, catalyst isn't really an acceptable alternative.

It looks like Catalyst uses some kind of "dynamic" dithering, like NVIDIA's proprietary drivers, which generates different noise everytime the screen is refreshed, so isn't really noticeable.

Does attachment 99834 [details] [review] help?

Created attachment 99983 [details] [review]
fix

This patch should fix the issue.

It works! Thank you!

(In reply to comment #27)
> Created attachment 99983 [details] [review] [review]
> fix
> 
> This patch should fix the issue.

I tested patch against 3.13 and it works. I assume it will fix later kernels too.

Well, I think we can close it as fix is now in stable and longterm kernels (except 3.12). :)