[Bug 17125] New: PLLs chosen that cause flicker on dual-link DVI monitor.

[bugzilla-daemon at freedesktop.org]

http://bugs.freedesktop.org/show_bug.cgi?id=17125

           Summary: PLLs chosen that cause flicker on dual-link DVI monitor.
           Product: xorg
           Version: git
          Platform: Other
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: medium
         Component: Driver/Radeon
        AssignedTo: xorg-driver-ati at lists.x.org
        ReportedBy: chris-fdbugs at printf.net
         QAContact: xorg-team at lists.x.org


Hi,

Radeon commit 72feaa37ea07620f5f2ead438dbc72a1c8883cd3 ("prefer lower ref
dividers..") causes flicker here, on a Radeon HD 3450 connected to an Apple 30"
cinema display.  The PLL settings are different before and after the patch, so
that's a likely culprit.

Before (working):  

http://dev.laptop.org/~cjb/xorg-noflicker.log

After (broken):

http://dev.laptop.org/~cjb/xorg-flicker.log

In particular, before:

best_freq: 268000000
best_feedback_div: 1072
best_ref_div: 27
best_post_div: 4
(II) RADEON(0): crtc(0) PLL  : refdiv 27, fbdiv 0x430(1072), pdiv 4

and after:

best_freq: 268000000
best_feedback_div: 268
best_ref_div: 9
best_post_div: 3
(II) RADEON(0): crtc(0) PLL  : refdiv 9, fbdiv 0x10C(268), pdiv 3


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