Bug triggered ?: intel and/or glamor

Hello, Since the introduction of Asynchronous page-flipping, in Linux kernel 5.11, Adding some code like:

... mode_config->funcs = &intel_mode_funcs;

    if (INTEL_GEN(i915) >= 9)
            mode_config->async_page_flip = true;

... in linux-5.11/drivers/gpu/drm/i915/display/intel_display.c

Makes Xorg hang : video and keyboard/mouse .

The faulty module is Glamor, which by disabeling it, makes Xorg dont hang while using openGL applications.

The error messages are tens of thousands of this:

modeset(0): flip queue failed: Invalid argument modeset(0): Page flip failed: Invalid argument modeset(0): present flip failed

Regards

X.Org X Server 1.20.10 Module glamoregl 1.0.1