[Bug 60523] Radeon DPM not working with 2 monitors attached to Radeon HD5770 (Juniper)

[bugzilla-daemon@bugzilla.kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=60523

--- Comment #31 from Alex Deucher <alexdeucher@gmail.com> ---
(In reply to Christian Birchinger from comment #30)
> Maybe the same reason why Tobias is stuck at level 2.
> 

Right you both seem to be afflicted but the same issue.

> Since i'm no longer able to use tools like xvidtune and the online modeline
> calculator tells me 1600x1200 85hz requires >300Mhz pixel clock, so i'm
> probably
> stuck at trying out lots of predefined modes that got pasted online.

You can use gtf or cvt to generate modelines and add them manually with xrandr.

> 
> How would i calculate the vblank period from modelines? It would really help
> if i at least knew a mode is within the specs before trying it out.

See r600_dpm_get_vblank_time() in r600_dpm.c for the formula:

line_time_us = (mode.crtc_htotal * 1000) / mode.clock;
vblank_lines = mode.crtc_vblank_end - mode.crtc_vdisplay;
vblank_time_us = vblank_lines * line_time_us;

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