modesetting: Fix possible_crtcs

Populate outout possible_crtcs as the union of possible_crtcs from the encoders rather than the intersection. Otherwise we're easily left with possible_crtcs==0 when all the possible encoders have non-overlapping possible_crtcs.

No idea what the magic 0x7f is about, but keep it around in case it matters.

Signed-off-by: Ville Syrjälä ville.syrjala@linux.intel.com

For the 0x7f, it seems come from: https://github.com/freedesktop/xorg-xf86-video-ati/commit/2f680b631357661511456f07b7b4ba1aa2cbf30c

And the limitation removed there at: https://github.com/freedesktop/xorg-xf86-video-ati/commit/5ec34ed95948f7164184551615c1fc4c3eef3b98

Cargo cult in action. And looks like -ati has the same bug :(

mentioned in commit elongbug/drm-tip@e838bfa8

mentioned in commit drm/msm@485f682b

mentioned in commit lyudess/linux@850fee72

added 68 commits

• c556960a...334f1107 - 67 commits from branch xorg:master
• 0e4bd71d - modesetting: Fix possible_crtcs

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enabled an automatic merge when the pipeline for 0e4bd71d succeeds

merged

mentioned in commit lyudess/linux@25208ab8