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Description
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With radeon driver, when MergedFB mode is used, on JDS the desktop resolution selection
capplet shows all negative refresh rates preventing resolution selection.
Open source bug:
[ Bug 6966 ] large negative refresh rates reported
The cause of the problem seems to be inappropriate setting of clock for the
merged mode, as seen in this portion of code
mode->Clock = (((i->Clock >> 3) + i->HTotal) << 16) | ((j->Clock >> 2) +
j->HTotal);
mode->Clock ^= ((i->VTotal << 19) | (j->VTotal << 3));
in RADEONCopyModeNLink() of radeon_mergedfb.c, where i and j represent two
modes to be merged, and the clock generated is a bogus negative number.
Talking to open source community Alex Deucher ( xxxxx@xxxxx.com), and know
that the intention of such clock setting it to make modes with same resolution
bug different refresh rates unique so that some other processing routine such as
xrandr can distinguish them (instead of throwing out one of them). But in reality
even with this kind of clock setting, so such uniqueness is ensured. Alex agrees
we need to investigate for a better solution.
Removing this portion of code solve the problem.
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