[Nouveau] [Bug 40747] The new nouveau kernel module fails to use my monitor's native resolution

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=40747

--- Comment #4 from monnier at iro.umontreal.ca 2011-09-09 20:55:52 PDT ---
> 2.6.32 kernel allowed to use higher resolution because it didn't take into
> account hardware limitations - NV44's tmds maximum pixel clock is 155MHz and
> 1600x1200 needs 162MHz.

Hmm... I must admit I had no idea of such a limitation.  And I've had this
machine for 5 years or so, now.  I've always used it at 1600x1200.  At the
beginning, I used it at that resolution via VGA rather than DVI (not sure if
that tmds limit applies to VGA), but the nvidia driver was also happy to set it
to 1600x1200 over DVI (tho the nv driver always limited itself to 1280x1024
over DVI, which is why I used VGA until nouveau matured).  And ever since
nouveau's kernel module started to work, I've used it for 1600x1200 over DVI.

I must say I'm shocked that a graphics card of the 21st century would not be
able to go up to 1600x1200.  Hell, my old Matrox Millenium II went up to
1800x1400 without complaining, more than 15 years ago.  Are you *really* sure
of this 155 limit?

So I guess I have 2 options:
- find a way to convince nouveau to go past this limit.  Could we get an option
  to get back the pre-2.6.37 behavior of limiting the tmds to 165?
- find a way to tell nouveau to use a modeline which gives me 1600x1200 but
  without the annoying "non optimal mode" warning on my monitor.
  Is there a way to get finer control on the modeline than "video=NNNxMMM"?

BTW, the 3.0.0-1 log shows that providing a "video=1600x1200" argument
convinces nouveau to use 1600x1200 and while it doesn't use the native modeline
(at 162Mhz) it does use a modeline at more than 155MHz:

[    7.316860] [drm:drm_mode_debug_printmodeline], Modeline 48:"1600x1200" 0
160961 1600 1704 1880 2160 1200 1201 1204 1242 0x0 0x6

Not sure where that modeline comes from, nor why nouveau seems to ignore the
155MHz limit for it.

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