1718386 - washed out colors, blurry text, semi-transparent window when WebRender active

Status: RESOLVED DUPLICATE of bug 1714483

(Core :: Graphics: WebRender, defect)

Description

[sbucc]

Attachment: Screenshot of Firefox 89.0.1 (same for 89.0.2)

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:89.0) Gecko/20100101 Firefox/89.0

Steps to reproduce:

Start Firefox with default settings. The windows shows the symptoms in title, making it effectively unusable, see attached screenshot.
Verified on version 89.0.1 and 89.0.2, on Xubuntu 20.04, Nvidia 970 card.
*Does not occur on Windows 10
*Does not occur on v75 (previous from apt repository)

Actual results:

The windows has washed-out colors, blurry text, and is semi-transparent, making it effectively unusable, see attached screenshot. Washed-out colors probably caused by transparency.
SOLUTION:
Disable WebRender (gfx.webrender.force-disabled = true), as suggested by @cor-el on the mozilla forum (https://support.mozilla.org/en-US/questions/1341828)

Expected results:

readable text, non-transparent window, correct colors.

Comment 1

[BugBot [:suhaib / :marco/ :calixte]]

The Bugbug bot thinks this bug should belong to the 'Core::Graphics: WebRender' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

Comment 2

[sbucc]

NVIDIA Driver Version: 460.80

Comment 3

[Darkspirit]

Does this problem still occur with https://nightly.mozilla.org ?

Comment 4

[sbucc]

(In reply to Darkspirit from comment #3)

Does this problem still occur with https://nightly.mozilla.org ?

The problem is FIXED with the latest nightly: firefox-91.0a1.en-GB.linux-x86_64.tar.bz2

Comment 5

[sbucc]

(In reply to sbucc from comment #4)

(In reply to Darkspirit from comment #3)

Does this problem still occur with https://nightly.mozilla.org ?

The problem is FIXED with the latest nightly: firefox-91.0a1.en-GB.linux-x86_64.tar.bz2

for clarity: I made sure that gfx.webrender.force-disabled = false (default setting), and also checked with gfx.webrender.enabled = true (default is false).

Comment 6

[Darkspirit]

Nice! Please try to find the commit that fixed this bug (at the end you should get a pushlog URL):
$ pip3 install --user mozregression
$ mozregression --find-fix --bad 89 --good 2021-07-06 --pref gfx.webrender.all:true

Comment 7

[sbucc]

Mmh... something fishy is going on. I installed mozregression as instructed, and found it BAD. There is a difference though: I had downloaded and tested the en-GB version (downloaded by default), while mozregression used the en-US version. I downloaded the same file and ran it outside mozregression, and still same BAD rendering. So, it appears that there are differences between the two localizations.
I also tried to run without '--pref gfx.webrender.all:true', as the default is false, but still BAD rendering.

Comment 8

[sbucc]

I'm almost certain that there is an issue with mixing configuration files between the different versions. Assuming mozregression keeps its config completely separate from whatever is on the disk, I can only conclude that both 92.0a1 and 92.0a1 nightlies still have the bug, and any time I was seeing good rendering it was just down to using the wrong configuration.

I'll just list my findings, and let someone else with deeper knowledge of firefox draw their conclusions:

1. I re-unpacked firefox-91.0a1.en-GB.linux-x86_64.tar.bz2, and it came up BAD: the rendering is just as borked as mainstream version 89. I would've sworn that it was GOOD one week ago.
2. However, on the next run, it automatically updated to 92.0a1, which ran GOOD. This happened for both en-US and en-GB versions.
3. I tried to run 'mozregression --find-fix --bad 89 --good 2021-07-15 --pref gfx.webrender.all:true': it ran 92.0a1 but it was BAD. Same for 'mozregression --find-fix --bad 89 --good 2021-07-15'.
4. I downloaded firefox-92.0a1.en-US.linux-x86_64.tar.bz2 directly, unpacked, ran and it was also BAD

Here it gets weirder:

5. I re-unpacked firefox-92.0a1.en-US.linux-x86_64.tar.bz2, and this time the main window was GOOD, but the 'about' window was BAD. I closed and restarted a number of times, and it always comes up main: GOOD, about: BAD.

In conclusion: I need to know the correct steps to make sure that I'm running with a clean configuration each time, otherwise I'm just wasting my time. But my opinion at the moment is that the bug is still present in the latest nightly.

Comment 9

[sbucc]

Attachment: firefox_92.0a1: Main window GOOD, about BAD

Screenshot of nightly 92.0a1 showing correct rendering for the main window, but incorrect rendering for the 'about' window.

Comment 10

[Darkspirit]

Please open NVIDIA X Server Settings > X Screen 0 > Antialiasing Settings and check if you have manually enabled FXAA. It could be the cause. (bug 1714483)

Comment 11

[sbucc]

@Darkspirit, you're right: it is the same bug. It seems to be an old issue too (https://www.reddit.com/r/archlinux/comments/fw7obn/this_is_mildly_interesting_with_nvidia_fxaa/).
The behaviour is different for main and nightly branch. The main branch shows the bug on both main and 'about' windows.
I tried to check the nightly branch too but I get inconsistent behaviour, which seems to depend on what has been run before (either main or nightly branch). Therefore from now on I'm not checking the nightly branch.

Comment 12

[Darkspirit]

Great, thanks for the confirmation!