1838586 - Disappearing letters and UI elements when using Webrender HW rendering

Status: UNCONFIRMED

(Firefox for Android :: Browser Engine, defect)

Description

[Emil S]

Attachment: ff_debug.txt

Steps to reproduce:

I tried running Fenix on an NXP i.MX 8M Plus board, which is running Android 10. Initially, the responsiveness of the UI was very slow, delaying any input significantly. I then force-enabled HW-Webrender with the flags

user_pref("gfx.webrender.all", true);
user_pref("gfx.webrender.enabled", true);
user_pref("gfx.webrender.compositor", true);
user_pref("gfx.webrender.software", false);
user_pref("gfx.webrender.compositor.force-enabled", true);

After enabling Hardware rendering this way, the UI had improved responsiveness, but now shows visual glitches with letters and (parts of) UI-Elements disappearing. This effect gets worse if one scrolls a lot up and down on a website.

I found that the graphics chip on this NXP board, the Vivante GC7000UL, was disabled for HW Webrender due to Bug 1719327. However, since I was able to enable HW Webrender and did not encounter an immediate crash, this bug does not seem applicable to this hardware.

Disabling HW rendering will make the sites render correctly, but they have significant input lag (occasionally >1 second for typed letters to show up or a scrolling action to be recognized). So effectively, I am forced to choose between significant input lag and visual glitches.

I've attached the output of about:support as a txt file.

Actual results:

Parts of the UI, especially letters, disappear at random, see also this screenshot: https://imgur.com/a/QfhbYRF. I initially observed this when using a custom version of the Reference browser, but the most recent nightly, as well as Fenix v114 both show this behavior as well.

I also tried both setting gfx.webrender.allow-partial-present-buffer-age to false and setting gfx.webrender.max-partial-present-rects to 0, as responses to similar bugs have already suggested, but both did not solve my problem.

Expected results:

No UI Elements should disappear/flicker when enabling HW Webrender.

Comment 1

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

The severity field is not set for this bug.
:jonalmeida, could you have a look please?

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