When modifiers are enabled on mutter on some of the older i915 systems observed
Black-screen on 2nd monitor during multi-head use cases, upon debugging observed
that disabling modifiers on these systems resolved the Black-screen issue:!1618.
This issue depends whether we have enough DBuf space to provide required bandwidth
for the userspace demands. Those platforms which have less Display Buffer, will
just have more chance to face lack of it. However it still depends on various
factors like amount of planes(i.e the more planes we have, the more we divide the buffer),
refresh rate, bpp and so on.
This affects watermark calculations and the minimum blocks required for at least
wm level 0. If we don't have sufficient ddb at least for wm0 for all planes in
the configuration then it is rejected.
Until we have TEST_ONLY commit solution is built we could make sure to disable
modifiers support on these older i915 systems based on udev rules defined in this commit.
This commit makes sure that modifiers are still usable on latest i915 systems.
List of PCI-IDs are referred from:
f8bf2a9a15/include/pci_ids/iris_pci_ids.h
Related: https://gitlab.gnome.org/GNOME/mutter/-/issues/1618
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2641>
9fab8410d7
